Search2024 Vol. 31, No. 6
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2024, vol. 31, no. 6, pp.
1167-1176.
https://doi.org/10.1007/s12613-024-2901-0
Abstract:
Shearing dislocation is a common failure type for rock–backfill interfaces because of backfill sedimentation and rock strata movement in backfill mining goaf. This paper designed a test method for rock–backfill shearing dislocation. Using digital image technology and three-dimensional (3D) laser morphology scanning techniques, a set of 3D models with rough joint surfaces was established. Further, the mechanical behavior of rock–backfill shearing dislocation was investigated using a direct shear test. The effects of interface roughness on the shear–displacement curve and failure characteristics of rock–backfill specimens were considered. The 3D fractal dimension, profile line joint roughness coefficient (JRC), profile line two-dimensional fractal dimension, and the surface curvature of the fractures were obtained. The correlation characterization of surface roughness was then analyzed, and the shear strength could be measured and calculated using JRC. The results showed the following: there were three failure threshold value points in rock–backfill shearing dislocation: 30%–50% displacement before the peak, 70%–90% displacement before the peak, and 100% displacement before the peak to post-peak, which could be a sign for rock–backfill shearing dislocation failure. The surface JRC could be used to judge the rock–backfill shearing dislocation failure, including post-peak sliding, uniform variations, and gradient change, corresponding to rock–backfill dislocation failure on the field site. The research reveals the damage mechanism for rock–backfill complexes based on the free joint surface, fills the gap of existing shearing theoretical systems for isomerism complexes, and provides a theoretical basis for the prevention and control of possible disasters in backfill mining.
Shearing dislocation is a common failure type for rock–backfill interfaces because of backfill sedimentation and rock strata movement in backfill mining goaf. This paper designed a test method for rock–backfill shearing dislocation. Using digital image technology and three-dimensional (3D) laser morphology scanning techniques, a set of 3D models with rough joint surfaces was established. Further, the mechanical behavior of rock–backfill shearing dislocation was investigated using a direct shear test. The effects of interface roughness on the shear–displacement curve and failure characteristics of rock–backfill specimens were considered. The 3D fractal dimension, profile line joint roughness coefficient (JRC), profile line two-dimensional fractal dimension, and the surface curvature of the fractures were obtained. The correlation characterization of surface roughness was then analyzed, and the shear strength could be measured and calculated using JRC. The results showed the following: there were three failure threshold value points in rock–backfill shearing dislocation: 30%–50% displacement before the peak, 70%–90% displacement before the peak, and 100% displacement before the peak to post-peak, which could be a sign for rock–backfill shearing dislocation failure. The surface JRC could be used to judge the rock–backfill shearing dislocation failure, including post-peak sliding, uniform variations, and gradient change, corresponding to rock–backfill dislocation failure on the field site. The research reveals the damage mechanism for rock–backfill complexes based on the free joint surface, fills the gap of existing shearing theoretical systems for isomerism complexes, and provides a theoretical basis for the prevention and control of possible disasters in backfill mining.
2024, vol. 31, no. 6, pp.
1177-1197.
https://doi.org/10.1007/s12613-024-2874-z
Abstract:
The flotation of complex solid–liquid multiphase systems involve interactions among multiple components, the core problem facing flotation theory. Meanwhile, the combined use of multicomponent flotation reagents to improve mineral flotation has become an important issue in studies on the efficient use of refractory mineral resources. However, studying the flotation of complex solid–liquid systems is extremely difficult, and no systematic theory has been developed to date. In addition, the physical mechanism associated with combining reagents to improve the flotation effect has not been unified, which limits the development of flotation theory and the progress of flotation technology. In this study, we applied theoretical thermodynamics to a solid–liquid flotation system and used changes in the entropy and Gibbs free energy of the reagents adsorbed on the mineral surface to establish thermodynamic equilibrium equations that describe interactions among various material components while also introducing adsorption equilibrium constants for the flotation reagents adsorbed on the mineral surface. The homogenization effect on the mineral surface in pulp solution was determined using the chemical potentials of the material components of the various mineral surfaces required to maintain balance. The flotation effect can be improved through synergy among multicomponent flotation reagents; its physical essence is the thermodynamic law that as the number of components of flotation reagents on the mineral surface increases, the surface adsorption entropy change increases, and the Gibbs free energy change of adsorption decreases. According to the results obtained using flotation thermodynamics theory, we established high-entropy flotation theory and a technical method in which increasing the types of flotation reagents adsorbed on the mineral surface, increasing the adsorption entropy change of the flotation reagents, decreasing the Gibbs free energy change, and improving the adsorption efficiency and stability of the flotation reagents improves refractory mineral flotation.
The flotation of complex solid–liquid multiphase systems involve interactions among multiple components, the core problem facing flotation theory. Meanwhile, the combined use of multicomponent flotation reagents to improve mineral flotation has become an important issue in studies on the efficient use of refractory mineral resources. However, studying the flotation of complex solid–liquid systems is extremely difficult, and no systematic theory has been developed to date. In addition, the physical mechanism associated with combining reagents to improve the flotation effect has not been unified, which limits the development of flotation theory and the progress of flotation technology. In this study, we applied theoretical thermodynamics to a solid–liquid flotation system and used changes in the entropy and Gibbs free energy of the reagents adsorbed on the mineral surface to establish thermodynamic equilibrium equations that describe interactions among various material components while also introducing adsorption equilibrium constants for the flotation reagents adsorbed on the mineral surface. The homogenization effect on the mineral surface in pulp solution was determined using the chemical potentials of the material components of the various mineral surfaces required to maintain balance. The flotation effect can be improved through synergy among multicomponent flotation reagents; its physical essence is the thermodynamic law that as the number of components of flotation reagents on the mineral surface increases, the surface adsorption entropy change increases, and the Gibbs free energy change of adsorption decreases. According to the results obtained using flotation thermodynamics theory, we established high-entropy flotation theory and a technical method in which increasing the types of flotation reagents adsorbed on the mineral surface, increasing the adsorption entropy change of the flotation reagents, decreasing the Gibbs free energy change, and improving the adsorption efficiency and stability of the flotation reagents improves refractory mineral flotation.
2024, vol. 31, no. 6, pp.
1198-1207.
https://doi.org/10.1007/s12613-023-2697-3
Abstract:
Flotation separation of calcite from fluorite is a challenge on low-grade fluorite flotation that limits the recovery and purity of fluorite concentrate. A new acid leaching–flotation process for fluorite is proposed in this work. This innovative process raised the fluorite’s grade to 97.26wt% while producing nanoscale calcium carbonate from its leachate, which contained plenty of calcium ions. On the production of nanoscale calcium carbonate, the impacts of concentration, temperature, and titration rate were examined. By modifying the process conditions and utilizing crystal conditioning agents, calcite-type and amorphous calcium carbonates with corresponding particle sizes of 1.823 and 1.511 μm were produced. The influence of the impurity ions Mn2+, Mg2+, and Fe3+ was demonstrated to reduce the particle size of nanoscale calcium carbonate and make crystal shape easier to manage in the fluorite leach solution system compared with the calcium chloride solution. The combination of the acid leaching–flotation process and the nanoscale calcium carbonate preparation method improved the grade of fluorite while recovering calcite resources, thus presenting a novel idea for the effective and clean usage of low-quality fluorite resources with embedded microfine particles.
Flotation separation of calcite from fluorite is a challenge on low-grade fluorite flotation that limits the recovery and purity of fluorite concentrate. A new acid leaching–flotation process for fluorite is proposed in this work. This innovative process raised the fluorite’s grade to 97.26wt% while producing nanoscale calcium carbonate from its leachate, which contained plenty of calcium ions. On the production of nanoscale calcium carbonate, the impacts of concentration, temperature, and titration rate were examined. By modifying the process conditions and utilizing crystal conditioning agents, calcite-type and amorphous calcium carbonates with corresponding particle sizes of 1.823 and 1.511 μm were produced. The influence of the impurity ions Mn2+, Mg2+, and Fe3+ was demonstrated to reduce the particle size of nanoscale calcium carbonate and make crystal shape easier to manage in the fluorite leach solution system compared with the calcium chloride solution. The combination of the acid leaching–flotation process and the nanoscale calcium carbonate preparation method improved the grade of fluorite while recovering calcite resources, thus presenting a novel idea for the effective and clean usage of low-quality fluorite resources with embedded microfine particles.
2024, vol. 31, no. 6, pp.
1208-1227.
https://doi.org/10.1007/s12613-023-2785-4
Abstract:
Natural minerals, such as kaolinite, halloysite, montmorillonite, attapulgite, bentonite, sepiolite, forsterite, and wollastonite, have considerable potential for use in CO2 capture and mineralization due to their abundant reserves, low cost, excellent mechanical properties, and chemical stability. Over the past decades, various methods, such as those involving heat, acid, alkali, organic amine, amino silane, and ionic liquid, have been employed to enhance the CO2 capture performance of natural minerals to attain high specific surface area, a large number of pore structures, and rich active sites. Future research on CO2 capture by natural minerals will focus on the full utilization of the properties of natural minerals, adoption of suitable modification methods, and preparation of composite materials with high specific surface area and rich active sites. In addition, we provide a summary of the principle and technical route of direct and indirect mineralization of CO2 by natural minerals. This process uses minerals with high calcium and magnesium contents, such as forsterite (Mg2SiO4), serpentine [Mg3Si2O(OH)4], and wollastonite (CaSiO3). The research status of indirect mineralization of CO2 using hydrochloric acid, acetic acid, molten salt, and ammonium salt as media is also introduced in detail. The recovery of additives and high-value-added products during the mineralization process to increase economic benefits is another focus of future research on CO2 mineralization by natural minerals.
Natural minerals, such as kaolinite, halloysite, montmorillonite, attapulgite, bentonite, sepiolite, forsterite, and wollastonite, have considerable potential for use in CO2 capture and mineralization due to their abundant reserves, low cost, excellent mechanical properties, and chemical stability. Over the past decades, various methods, such as those involving heat, acid, alkali, organic amine, amino silane, and ionic liquid, have been employed to enhance the CO2 capture performance of natural minerals to attain high specific surface area, a large number of pore structures, and rich active sites. Future research on CO2 capture by natural minerals will focus on the full utilization of the properties of natural minerals, adoption of suitable modification methods, and preparation of composite materials with high specific surface area and rich active sites. In addition, we provide a summary of the principle and technical route of direct and indirect mineralization of CO2 by natural minerals. This process uses minerals with high calcium and magnesium contents, such as forsterite (Mg2SiO4), serpentine [Mg3Si2O(OH)4], and wollastonite (CaSiO3). The research status of indirect mineralization of CO2 using hydrochloric acid, acetic acid, molten salt, and ammonium salt as media is also introduced in detail. The recovery of additives and high-value-added products during the mineralization process to increase economic benefits is another focus of future research on CO2 mineralization by natural minerals.
2024, vol. 31, no. 6, pp.
1228-1240.
https://doi.org/10.1007/s12613-023-2693-7
Abstract:
The prediction and control of furnace heat indicators are of great importance for improving the heat levels and conditions of the complex and difficult-to-operate hour-class delay blast furnace (BF) system. In this work, a prediction and feedback model of furnace heat indicators based on the fusion of data-driven and BF ironmaking processes was proposed. The data on raw and fuel materials, process operation, smelting state, and slag and iron discharge during the whole BF process comprised 171 variables with 9223 groups of data and were comprehensively analyzed. A novel method for the delay analysis of furnace heat indicators was established. The extracted delay variables were found to play an important role in modeling. The method that combined the genetic algorithm and stacking efficiently improved performance compared with the traditional machine learning algorithm in improving the hit ratio of the furnace heat prediction model. The hit ratio for predicting the temperature of hot metal in the error range of ±10°C was 92.4%, and that for the chemical heat of hot metal in the error range of ±0.1wt% was 93.3%. On the basis of the furnace heat prediction model and expert experience, a feedback model of furnace heat operation was established to obtain quantitative operation suggestions for stabilizing BF heat levels. These suggestions were highly accepted by BF operators. Finally, the comprehensive and dynamic model proposed in this work was successfully applied in a practical BF system. It improved the BF temperature level remarkably, increasing the furnace temperature stability rate from 54.9% to 84.9%. This improvement achieved considerable economic benefits.
The prediction and control of furnace heat indicators are of great importance for improving the heat levels and conditions of the complex and difficult-to-operate hour-class delay blast furnace (BF) system. In this work, a prediction and feedback model of furnace heat indicators based on the fusion of data-driven and BF ironmaking processes was proposed. The data on raw and fuel materials, process operation, smelting state, and slag and iron discharge during the whole BF process comprised 171 variables with 9223 groups of data and were comprehensively analyzed. A novel method for the delay analysis of furnace heat indicators was established. The extracted delay variables were found to play an important role in modeling. The method that combined the genetic algorithm and stacking efficiently improved performance compared with the traditional machine learning algorithm in improving the hit ratio of the furnace heat prediction model. The hit ratio for predicting the temperature of hot metal in the error range of ±10°C was 92.4%, and that for the chemical heat of hot metal in the error range of ±0.1wt% was 93.3%. On the basis of the furnace heat prediction model and expert experience, a feedback model of furnace heat operation was established to obtain quantitative operation suggestions for stabilizing BF heat levels. These suggestions were highly accepted by BF operators. Finally, the comprehensive and dynamic model proposed in this work was successfully applied in a practical BF system. It improved the BF temperature level remarkably, increasing the furnace temperature stability rate from 54.9% to 84.9%. This improvement achieved considerable economic benefits.
2024, vol. 31, no. 6, pp.
1241-1248.
https://doi.org/10.1007/s12613-023-2800-9
Abstract:
Space metallurgy is an interdisciplinary field that combines planetary space science and metallurgical engineering. It involves systematic and theoretical engineering technology for utilizing planetary resources in situ. However, space metallurgy on the Moon is challenging because the lunar surface has experienced space weathering due to the lack of atmosphere and magnetic field, making the microstructure of lunar soil differ from that of minerals on the Earth. In this study, scanning electron microscopy and transmission electron microscopy analyses were performed on Chang’e-5 powder lunar soil samples. The microstructural characteristics of the lunar soil may drastically change its metallurgical performance. The main special structure of lunar soil minerals include the nanophase iron formed by the impact of micrometeorites, the amorphous layer caused by solar wind injection, and radiation tracks modified by high-energy particle rays inside mineral crystals. The nanophase iron presents a wide distribution, which may have a great impact on the electromagnetic properties of lunar soil. Hydrogen ions injected by solar wind may promote the hydrogen reduction process. The widely distributed amorphous layer and impact glass can promote the melting and diffusion process of lunar soil. Therefore, although high-energy events on the lunar surface transform the lunar soil, they also increase the chemical activity of the lunar soil. This is a property that earth samples and traditional simulated lunar soil lack. The application of space metallurgy requires comprehensive consideration of the unique physical and chemical properties of lunar soil.
Space metallurgy is an interdisciplinary field that combines planetary space science and metallurgical engineering. It involves systematic and theoretical engineering technology for utilizing planetary resources in situ. However, space metallurgy on the Moon is challenging because the lunar surface has experienced space weathering due to the lack of atmosphere and magnetic field, making the microstructure of lunar soil differ from that of minerals on the Earth. In this study, scanning electron microscopy and transmission electron microscopy analyses were performed on Chang’e-5 powder lunar soil samples. The microstructural characteristics of the lunar soil may drastically change its metallurgical performance. The main special structure of lunar soil minerals include the nanophase iron formed by the impact of micrometeorites, the amorphous layer caused by solar wind injection, and radiation tracks modified by high-energy particle rays inside mineral crystals. The nanophase iron presents a wide distribution, which may have a great impact on the electromagnetic properties of lunar soil. Hydrogen ions injected by solar wind may promote the hydrogen reduction process. The widely distributed amorphous layer and impact glass can promote the melting and diffusion process of lunar soil. Therefore, although high-energy events on the lunar surface transform the lunar soil, they also increase the chemical activity of the lunar soil. This is a property that earth samples and traditional simulated lunar soil lack. The application of space metallurgy requires comprehensive consideration of the unique physical and chemical properties of lunar soil.
2024, vol. 31, no. 6, pp.
1249-1262.
https://doi.org/10.1007/s12613-024-2878-8
Abstract:
After the converter steelmaking process, a considerable number of ferroalloys are needed to remove dissolved oxygen from the molten steel, but it also forms a lot of oxide inclusions that cannot be completely removed. At the same time, it increases the carbon emissions in the steel production process. After years of research, our team have developed a series of clean deoxidation technologies, including carbon deoxidation, hydrogen deoxidation, and waste plastic deoxidation of molten steel to address the aforementioned issues. In this study, thermodynamic calculations and laboratory experiments were employed to verify that carbon and hydrogen can reduce the total oxygen content in the molten steel melt to below 5 × 10−6 and 10 × 10−6, respectively. An analysis of the deoxidation mechanisms and effects of polyethylene and polypropylene was also conducted. In addition, the applications of carbon deoxidation technology in different steels with the hot-state experiment and industrial production were discussed carefully. The carbon deoxidation experimental results of different steels were as follows: (1) the oxygen content of bearing steel was effectively controlled at 6.3 × 10−6 and the inclusion number density was lowered by 74.73% compared to aluminum deoxidized bearing steel; (2) the oxygen content in gear steel was reduced to 7.7 × 10−6 and a 54.49% reduction of inclusion number density was achieved with almost no inclusions larger than 5 μm from the average level of industry gear steels; (3) a total oxygen content of M2 high-speed steel was as low as 3.7 × 10−6. In industrial production practice, carbon deoxidation technique was applied in the final deoxidation stage for non-aluminum deoxidized bearing steel, and it yielded excellent results that the oxygen content was reduced to below 8 × 10−6 and the oxide inclusions in the steel mainly consist of silicates, along with small amounts of spinel and calcium aluminate.
After the converter steelmaking process, a considerable number of ferroalloys are needed to remove dissolved oxygen from the molten steel, but it also forms a lot of oxide inclusions that cannot be completely removed. At the same time, it increases the carbon emissions in the steel production process. After years of research, our team have developed a series of clean deoxidation technologies, including carbon deoxidation, hydrogen deoxidation, and waste plastic deoxidation of molten steel to address the aforementioned issues. In this study, thermodynamic calculations and laboratory experiments were employed to verify that carbon and hydrogen can reduce the total oxygen content in the molten steel melt to below 5 × 10−6 and 10 × 10−6, respectively. An analysis of the deoxidation mechanisms and effects of polyethylene and polypropylene was also conducted. In addition, the applications of carbon deoxidation technology in different steels with the hot-state experiment and industrial production were discussed carefully. The carbon deoxidation experimental results of different steels were as follows: (1) the oxygen content of bearing steel was effectively controlled at 6.3 × 10−6 and the inclusion number density was lowered by 74.73% compared to aluminum deoxidized bearing steel; (2) the oxygen content in gear steel was reduced to 7.7 × 10−6 and a 54.49% reduction of inclusion number density was achieved with almost no inclusions larger than 5 μm from the average level of industry gear steels; (3) a total oxygen content of M2 high-speed steel was as low as 3.7 × 10−6. In industrial production practice, carbon deoxidation technique was applied in the final deoxidation stage for non-aluminum deoxidized bearing steel, and it yielded excellent results that the oxygen content was reduced to below 8 × 10−6 and the oxide inclusions in the steel mainly consist of silicates, along with small amounts of spinel and calcium aluminate.
2024, vol. 31, no. 6, pp.
1263-1284.
https://doi.org/10.1007/s12613-023-2754-y
Abstract:
The mechanisms of oxide metallurgy include inducing the formation of intragranular acicular ferrite (IAF) using micron-sized inclusions and restricting the growth of prior austenite grains (PAGs) by nanosized particles during welding. The chaotically oriented IAF and refined PAGs inhibit crack initiation and propagation in the steel, resulting in high impact toughness. This work summarizes the combined effect of deoxidizers and alloying elements, with the aim to provide a new perspective for the research and practice related to improving the impact toughness of the heat affected zone (HAZ) during the high heat input welding. Ti complex deoxidation with other strong deoxidants, such as Mg, Ca, Zr, and rare earth metals (REMs), can improve the toughness of the heat-affected zone (HAZ) by refining PAGs or increasing IAF contents. However, it is difficult to identify the specific phase responsible for IAF nucleation because effective inclusions formed by complex deoxidation are usually multiphase. Increasing alloying elements, such as C, Si, Al, Nb, or Cr, contents can impair HAZ toughness. A high C content typically increases the number of coarse carbides and decreases the potency of IAF formation. Si, Cr, or Al addition leads to the formation of undesirable microstructures. Nb reduces the high-temperature stability of the precipitates. Mo, V, and B can enhance HAZ toughness. Mo-containing precipitates present good thermal stability. VN or V(C,N) is effective in promoting IAF nucleation due to its good coherent crystallographic relationship with ferrite. The formation of the B-depleted zone around the inclusion promotes IAF formation. The interactions between alloying elements are complex, and the effect of adding different alloying elements remains to be evaluated. In the future, the interactions between various alloying elements and their effects on oxide metallurgy, as well as the calculation of the nucleation effects of effective inclusions using first principles calculations will become the focus of oxide metallurgy.
The mechanisms of oxide metallurgy include inducing the formation of intragranular acicular ferrite (IAF) using micron-sized inclusions and restricting the growth of prior austenite grains (PAGs) by nanosized particles during welding. The chaotically oriented IAF and refined PAGs inhibit crack initiation and propagation in the steel, resulting in high impact toughness. This work summarizes the combined effect of deoxidizers and alloying elements, with the aim to provide a new perspective for the research and practice related to improving the impact toughness of the heat affected zone (HAZ) during the high heat input welding. Ti complex deoxidation with other strong deoxidants, such as Mg, Ca, Zr, and rare earth metals (REMs), can improve the toughness of the heat-affected zone (HAZ) by refining PAGs or increasing IAF contents. However, it is difficult to identify the specific phase responsible for IAF nucleation because effective inclusions formed by complex deoxidation are usually multiphase. Increasing alloying elements, such as C, Si, Al, Nb, or Cr, contents can impair HAZ toughness. A high C content typically increases the number of coarse carbides and decreases the potency of IAF formation. Si, Cr, or Al addition leads to the formation of undesirable microstructures. Nb reduces the high-temperature stability of the precipitates. Mo, V, and B can enhance HAZ toughness. Mo-containing precipitates present good thermal stability. VN or V(C,N) is effective in promoting IAF nucleation due to its good coherent crystallographic relationship with ferrite. The formation of the B-depleted zone around the inclusion promotes IAF formation. The interactions between alloying elements are complex, and the effect of adding different alloying elements remains to be evaluated. In the future, the interactions between various alloying elements and their effects on oxide metallurgy, as well as the calculation of the nucleation effects of effective inclusions using first principles calculations will become the focus of oxide metallurgy.
2024, vol. 31, no. 6, pp.
1285-1297.
https://doi.org/10.1007/s12613-023-2751-1
Abstract:
Plastic instability, including both the discontinuous yielding and stress serrations, has been frequently observed during the tensile deformation of medium-Mn steels (MMnS) and has been intensively studied in recent years. Unfortunately, research results are controversial, and no consensus has been achieved regarding the topic. Here, we first summarize all the possible factors that affect the yielding and flow stress serrations in MMnS, including the morphology and stability of austenite, the feature of the phase interface, and the deformation parameters. Then, we propose a universal mechanism to explain the conflicting experimental results. We conclude that the discontinuous yielding can be attributed to the lack of mobile dislocation before deformation and the rapid dislocation multiplication at the beginning of plastic deformation. Meanwhile, the results show that the stress serrations are formed due to the pinning and depinning between dislocations and interstitial atoms in austenite. Strain-induced martensitic transformation, influenced by the mechanical stability of austenite grain and deformation parameters, should not be the intrinsic cause of plastic instability. However, it can intensify or weaken the discontinuous yielding and the stress serrations by affecting the mobility and density of dislocations, as well as the interaction between the interstitial atoms and dislocations in austenite grains.
Plastic instability, including both the discontinuous yielding and stress serrations, has been frequently observed during the tensile deformation of medium-Mn steels (MMnS) and has been intensively studied in recent years. Unfortunately, research results are controversial, and no consensus has been achieved regarding the topic. Here, we first summarize all the possible factors that affect the yielding and flow stress serrations in MMnS, including the morphology and stability of austenite, the feature of the phase interface, and the deformation parameters. Then, we propose a universal mechanism to explain the conflicting experimental results. We conclude that the discontinuous yielding can be attributed to the lack of mobile dislocation before deformation and the rapid dislocation multiplication at the beginning of plastic deformation. Meanwhile, the results show that the stress serrations are formed due to the pinning and depinning between dislocations and interstitial atoms in austenite. Strain-induced martensitic transformation, influenced by the mechanical stability of austenite grain and deformation parameters, should not be the intrinsic cause of plastic instability. However, it can intensify or weaken the discontinuous yielding and the stress serrations by affecting the mobility and density of dislocations, as well as the interaction between the interstitial atoms and dislocations in austenite grains.
2024, vol. 31, no. 6, pp.
1298-1310.
https://doi.org/10.1007/s12613-023-2781-8
Abstract:
High-strength steels are mainly composed of medium- or low-temperature microstructures, such as bainite or martensite, with coherent transformation characteristics. This type of microstructure has a high density of dislocations and fine crystallographic structural units, which ease the coordinated matching of high strength, toughness, and plasticity. Meanwhile, given its excellent welding performance, high-strength steel has been widely used in major engineering constructions, such as pipelines, ships, and bridges. However, visualization and digitization of the effective units of these coherent transformation structures using traditional methods (optical microscopy and scanning electron microscopy) is difficult due to their complex morphology. Moreover, the establishment of quantitative relationships with macroscopic mechanical properties and key process parameters presents additional difficulty. This article reviews the latest progress in microstructural visualization and digitization of high-strength steel, with a focus on the application of crystallographic methods in the development of high-strength steel plates and welding. We obtained the crystallographic data (Euler angle) of the transformed microstructures through electron back-scattering diffraction and combined them with the calculation of inverse transformation from bainite or martensite to austenite to determine the reconstruction of high-temperature parent austenite and orientation relationship (OR) during continuous cooling transformation. Furthermore, visualization of crystallographic packets, blocks, and variants based on actual OR and digitization of various grain boundaries can be effectively completed to establish quantitative relationships with alloy composition and key process parameters, thereby providing reverse design guidance for the development of high-strength steel.
High-strength steels are mainly composed of medium- or low-temperature microstructures, such as bainite or martensite, with coherent transformation characteristics. This type of microstructure has a high density of dislocations and fine crystallographic structural units, which ease the coordinated matching of high strength, toughness, and plasticity. Meanwhile, given its excellent welding performance, high-strength steel has been widely used in major engineering constructions, such as pipelines, ships, and bridges. However, visualization and digitization of the effective units of these coherent transformation structures using traditional methods (optical microscopy and scanning electron microscopy) is difficult due to their complex morphology. Moreover, the establishment of quantitative relationships with macroscopic mechanical properties and key process parameters presents additional difficulty. This article reviews the latest progress in microstructural visualization and digitization of high-strength steel, with a focus on the application of crystallographic methods in the development of high-strength steel plates and welding. We obtained the crystallographic data (Euler angle) of the transformed microstructures through electron back-scattering diffraction and combined them with the calculation of inverse transformation from bainite or martensite to austenite to determine the reconstruction of high-temperature parent austenite and orientation relationship (OR) during continuous cooling transformation. Furthermore, visualization of crystallographic packets, blocks, and variants based on actual OR and digitization of various grain boundaries can be effectively completed to establish quantitative relationships with alloy composition and key process parameters, thereby providing reverse design guidance for the development of high-strength steel.
2024, vol. 31, no. 6, pp.
1311-1321.
https://doi.org/10.1007/s12613-023-2661-2
Abstract:
Traditional 3Ni weathering steel cannot completely meet the requirements for offshore engineering development, resulting in the design of novel 3Ni steel with the addition of microalloy elements such as Mn or Nb for strength enhancement becoming a trend. The stress-assisted corrosion behavior of a novel designed high-strength 3Ni steel was investigated in the current study using the corrosion big data method. The information on the corrosion process was recorded using the galvanic corrosion current monitoring method. The gradient boosting decision tree (GBDT) machine learning method was used to mine the corrosion mechanism, and the importance of the structure factor was investigated. Field exposure tests were conducted to verify the calculated results using the GBDT method. Results indicated that the GBDT method can be effectively used to study the influence of structural factors on the corrosion process of 3Ni steel. Different mechanisms for the addition of Mn and Cu to the stress-assisted corrosion of 3Ni steel suggested that Mn and Cu have no obvious effect on the corrosion rate of non-stressed 3Ni steel during the early stage of corrosion. When the corrosion reached a stable state, the increase in Mn element content increased the corrosion rate of 3Ni steel, while Cu reduced this rate. In the presence of stress, the increase in Mn element content and Cu addition can inhibit the corrosion process. The corrosion law of outdoor-exposed 3Ni steel is consistent with the law based on corrosion big data technology, verifying the reliability of the big data evaluation method and data prediction model selection.
Traditional 3Ni weathering steel cannot completely meet the requirements for offshore engineering development, resulting in the design of novel 3Ni steel with the addition of microalloy elements such as Mn or Nb for strength enhancement becoming a trend. The stress-assisted corrosion behavior of a novel designed high-strength 3Ni steel was investigated in the current study using the corrosion big data method. The information on the corrosion process was recorded using the galvanic corrosion current monitoring method. The gradient boosting decision tree (GBDT) machine learning method was used to mine the corrosion mechanism, and the importance of the structure factor was investigated. Field exposure tests were conducted to verify the calculated results using the GBDT method. Results indicated that the GBDT method can be effectively used to study the influence of structural factors on the corrosion process of 3Ni steel. Different mechanisms for the addition of Mn and Cu to the stress-assisted corrosion of 3Ni steel suggested that Mn and Cu have no obvious effect on the corrosion rate of non-stressed 3Ni steel during the early stage of corrosion. When the corrosion reached a stable state, the increase in Mn element content increased the corrosion rate of 3Ni steel, while Cu reduced this rate. In the presence of stress, the increase in Mn element content and Cu addition can inhibit the corrosion process. The corrosion law of outdoor-exposed 3Ni steel is consistent with the law based on corrosion big data technology, verifying the reliability of the big data evaluation method and data prediction model selection.
2024, vol. 31, no. 6, pp.
1322-1332.
https://doi.org/10.1007/s12613-023-2745-z
Abstract:
Compared with traditional plastic forming, ultrasonic vibration plastic forming has the advantages of reducing the forming force and improving the surface quality of the workpiece. This technology has a very broad application prospect in industrial manufacturing. Researchers have conducted extensive research on the ultrasonic vibration plastic forming of metals and laid a deep foundation for the development of this field. In this review, metals were classified according to their crystal structures. The effects of ultrasonic vibration on the microstructure of face-centered cubic, body-centered cubic, and hexagonal close-packed metals during plastic forming and the mechanism underlying ultrasonic vibration forming were reviewed. The main challenges and future research direction of the ultrasonic vibration plastic forming of metals were also discussed.
Compared with traditional plastic forming, ultrasonic vibration plastic forming has the advantages of reducing the forming force and improving the surface quality of the workpiece. This technology has a very broad application prospect in industrial manufacturing. Researchers have conducted extensive research on the ultrasonic vibration plastic forming of metals and laid a deep foundation for the development of this field. In this review, metals were classified according to their crystal structures. The effects of ultrasonic vibration on the microstructure of face-centered cubic, body-centered cubic, and hexagonal close-packed metals during plastic forming and the mechanism underlying ultrasonic vibration forming were reviewed. The main challenges and future research direction of the ultrasonic vibration plastic forming of metals were also discussed.
2024, vol. 31, no. 6, pp.
1333-1349.
https://doi.org/10.1007/s12613-024-2840-9
Abstract:
High-entropy alloys (HEAs) possess outstanding features such as corrosion resistance, irradiation resistance, and good mechanical properties. A few HEAs have found applications in the fields of aerospace and defense. Extensive studies on the deformation mechanisms of HEAs can guide microstructure control and toughness design, which is vital for understanding and studying state-of-the-art structural materials. Synchrotron X-ray and neutron diffraction are necessary techniques for materials science research, especially for in situ coupling of physical/chemical fields and for resolving macro/microcrystallographic information on materials. Recently, several researchers have applied synchrotron X-ray and neutron diffraction methods to study the deformation mechanisms, phase transformations, stress behaviors, and in situ processes of HEAs, such as variable-temperature, high-pressure, and hydrogenation processes. In this review, the principles and development of synchrotron X-ray and neutron diffraction are presented, and their applications in the deformation mechanisms of HEAs are discussed. The factors that influence the deformation mechanisms of HEAs are also outlined. This review focuses on the microstructures and micromechanical behaviors during tension/compression or creep/fatigue deformation and the application of synchrotron X-ray and neutron diffraction methods to the characterization of dislocations, stacking faults, twins, phases, and intergrain/interphase stress changes. Perspectives on future developments of synchrotron X-ray and neutron diffraction and on research directions on the deformation mechanisms of novel metals are discussed.
High-entropy alloys (HEAs) possess outstanding features such as corrosion resistance, irradiation resistance, and good mechanical properties. A few HEAs have found applications in the fields of aerospace and defense. Extensive studies on the deformation mechanisms of HEAs can guide microstructure control and toughness design, which is vital for understanding and studying state-of-the-art structural materials. Synchrotron X-ray and neutron diffraction are necessary techniques for materials science research, especially for in situ coupling of physical/chemical fields and for resolving macro/microcrystallographic information on materials. Recently, several researchers have applied synchrotron X-ray and neutron diffraction methods to study the deformation mechanisms, phase transformations, stress behaviors, and in situ processes of HEAs, such as variable-temperature, high-pressure, and hydrogenation processes. In this review, the principles and development of synchrotron X-ray and neutron diffraction are presented, and their applications in the deformation mechanisms of HEAs are discussed. The factors that influence the deformation mechanisms of HEAs are also outlined. This review focuses on the microstructures and micromechanical behaviors during tension/compression or creep/fatigue deformation and the application of synchrotron X-ray and neutron diffraction methods to the characterization of dislocations, stacking faults, twins, phases, and intergrain/interphase stress changes. Perspectives on future developments of synchrotron X-ray and neutron diffraction and on research directions on the deformation mechanisms of novel metals are discussed.
2024, vol. 31, no. 6, pp.
1350-1363.
https://doi.org/10.1007/s12613-023-2777-4
Abstract:
High-entropy alloys (HEAs), which were introduced as a pioneering concept in 2004, have captured the keen interest of numerous researchers. Entropy, in this context, can be perceived as representing disorder and randomness. By contrast, elemental compositions within alloy systems occupy specific structural sites in space, a concept referred to as structure. In accordance with Shannon entropy, structure is analogous to information. Generally, the arrangement of atoms within a material, termed its structure, plays a pivotal role in dictating its properties. In addition to expanding the array of options for alloy composites, HEAs afford ample opportunities for diverse structural designs. The profound influence of distinct structural features on the exceptional behaviors of alloys is underscored by numerous examples. These features include remarkably high fracture strength with excellent ductility, antiballistic capability, exceptional radiation resistance, and corrosion resistance. In this paper, we delve into various unique material structures and properties while elucidating the intricate relationship between structure and performance.
High-entropy alloys (HEAs), which were introduced as a pioneering concept in 2004, have captured the keen interest of numerous researchers. Entropy, in this context, can be perceived as representing disorder and randomness. By contrast, elemental compositions within alloy systems occupy specific structural sites in space, a concept referred to as structure. In accordance with Shannon entropy, structure is analogous to information. Generally, the arrangement of atoms within a material, termed its structure, plays a pivotal role in dictating its properties. In addition to expanding the array of options for alloy composites, HEAs afford ample opportunities for diverse structural designs. The profound influence of distinct structural features on the exceptional behaviors of alloys is underscored by numerous examples. These features include remarkably high fracture strength with excellent ductility, antiballistic capability, exceptional radiation resistance, and corrosion resistance. In this paper, we delve into various unique material structures and properties while elucidating the intricate relationship between structure and performance.
2024, vol. 31, no. 6, pp.
1364-1372.
https://doi.org/10.1007/s12613-024-2892-x
Abstract:
The effect of W element on the microstructure evolution and mechanical properties of Al1.25CoCrFeNi3 eutectic high-entropy alloy and Al1.25CoCrFeNi3−xWx (x = 0, 0.05, 0.1, 0.3, and 0.5; atomic ratio) high-entropy alloys (HEAs) were explored. Results show that the Al1.25CoCrFeNi3−xWx HEAs are composed of face-centered cubic and body-centered cubic (BCC) phases. As W content increases, the microstructure changes from eutectic to dendritic. The addition of W lowers the nucleation barrier of the BCC phase, decreases the valence electron concentration of the HEAs, and replaces Al in the BCC phase, thus facilitating the nucleation of the BCC phase. Tensile results show that the addition of W greatly improves the mechanical properties, and solid-solution, heterogeneous-interface, and second-phase strengthening are the main strengthening mechanisms. The yield strength, tensile strength, and elongation of the Al1.25CoCrFeNi2.95W0.05 HEA are 601.44 MPa, 1132.26 MPa, and 15.94%, respectively, realizing a balance between strength and plasticity. The fracture mode of the Al1.25CoCrFeNi3−xWx HEAs is ductile–brittle mixed fracture, and the crack propagates and initiates in the BCC phase. The eutectic lamellar structure impedes crack propagation and maintains plasticity.
The effect of W element on the microstructure evolution and mechanical properties of Al1.25CoCrFeNi3 eutectic high-entropy alloy and Al1.25CoCrFeNi3−xWx (x = 0, 0.05, 0.1, 0.3, and 0.5; atomic ratio) high-entropy alloys (HEAs) were explored. Results show that the Al1.25CoCrFeNi3−xWx HEAs are composed of face-centered cubic and body-centered cubic (BCC) phases. As W content increases, the microstructure changes from eutectic to dendritic. The addition of W lowers the nucleation barrier of the BCC phase, decreases the valence electron concentration of the HEAs, and replaces Al in the BCC phase, thus facilitating the nucleation of the BCC phase. Tensile results show that the addition of W greatly improves the mechanical properties, and solid-solution, heterogeneous-interface, and second-phase strengthening are the main strengthening mechanisms. The yield strength, tensile strength, and elongation of the Al1.25CoCrFeNi2.95W0.05 HEA are 601.44 MPa, 1132.26 MPa, and 15.94%, respectively, realizing a balance between strength and plasticity. The fracture mode of the Al1.25CoCrFeNi3−xWx HEAs is ductile–brittle mixed fracture, and the crack propagates and initiates in the BCC phase. The eutectic lamellar structure impedes crack propagation and maintains plasticity.
2024, vol. 31, no. 6, pp.
1373-1381.
https://doi.org/10.1007/s12613-024-2843-6
Abstract:
A novel multicomponent high-Cr CoNi-based superalloy with superior comprehensive performance was prepared, and the evaluation of its high-temperature microstructural stability, oxidation resistance, and mechanical properties was conducted mainly using its cast polycrystalline alloy. The results disclosed that the morphology of the γ′ phase remained stable, and the coarsening rate was slow during the long-term aging at 900–1000°C. The activation energy for γ′ precipitate coarsening of alloy 9CoNi-Cr was (402 ± 51) kJ/mol, which is higher compared with those of CMSX-4 and some other Ni-based and Co-based superalloys. Importantly, there was no indication of the formation of topologically close-packed phases during this process. All these factors demonstrated the superior microstructural stability of the alloy. The mass gain of alloy 9CoNi-Cr was 0.6 mg/cm2 after oxidation at 1000°C for 100 h, and the oxidation resistance was comparable to advanced Ni-based superalloys CMSX-4, which can be attributed to the formation of a continuous Al2O3 protective layer. Moreover, the compressive yield strength of this cast polycrystalline alloy at high temperatures is clearly higher than that of the conventional Ni-based cast superalloy and the compressive minimum creep rate at 950°C is comparable to that of the conventional Ni-based cast superalloy, demonstrating the alloy’s good mechanical properties at high temperature. This is partially because high Cr is beneficial in improving the γ and γ′ phase strengths of alloy 9CoNi-Cr.
A novel multicomponent high-Cr CoNi-based superalloy with superior comprehensive performance was prepared, and the evaluation of its high-temperature microstructural stability, oxidation resistance, and mechanical properties was conducted mainly using its cast polycrystalline alloy. The results disclosed that the morphology of the γ′ phase remained stable, and the coarsening rate was slow during the long-term aging at 900–1000°C. The activation energy for γ′ precipitate coarsening of alloy 9CoNi-Cr was (402 ± 51) kJ/mol, which is higher compared with those of CMSX-4 and some other Ni-based and Co-based superalloys. Importantly, there was no indication of the formation of topologically close-packed phases during this process. All these factors demonstrated the superior microstructural stability of the alloy. The mass gain of alloy 9CoNi-Cr was 0.6 mg/cm2 after oxidation at 1000°C for 100 h, and the oxidation resistance was comparable to advanced Ni-based superalloys CMSX-4, which can be attributed to the formation of a continuous Al2O3 protective layer. Moreover, the compressive yield strength of this cast polycrystalline alloy at high temperatures is clearly higher than that of the conventional Ni-based cast superalloy and the compressive minimum creep rate at 950°C is comparable to that of the conventional Ni-based cast superalloy, demonstrating the alloy’s good mechanical properties at high temperature. This is partially because high Cr is beneficial in improving the γ and γ′ phase strengths of alloy 9CoNi-Cr.
2024, vol. 31, no. 6, pp.
1382-1391.
https://doi.org/10.1007/s12613-023-2782-7
Abstract:
Ni-based superalloys are one of the most important materials employed in high-temperature applications within the aerospace and nuclear energy industries and in gas turbines due to their excellent corrosion, radiation, fatigue resistance, and high-temperature strength. Linear friction welding (LFW) is a new joining technology with near-net-forming characteristics that can be used for the manufacture and repair of a wide range of aerospace components. This paper reviews published works on LFW of Ni-based superalloys with the aim of understanding the characteristics of frictional heat generation and extrusion deformation, microstructures, mechanical properties, flash morphology, residual stresses, creep, and fatigue of Ni-based superalloy weldments produced with LFW to enable future optimum utilization of the LFW process.
Ni-based superalloys are one of the most important materials employed in high-temperature applications within the aerospace and nuclear energy industries and in gas turbines due to their excellent corrosion, radiation, fatigue resistance, and high-temperature strength. Linear friction welding (LFW) is a new joining technology with near-net-forming characteristics that can be used for the manufacture and repair of a wide range of aerospace components. This paper reviews published works on LFW of Ni-based superalloys with the aim of understanding the characteristics of frictional heat generation and extrusion deformation, microstructures, mechanical properties, flash morphology, residual stresses, creep, and fatigue of Ni-based superalloy weldments produced with LFW to enable future optimum utilization of the LFW process.
2024, vol. 31, no. 6, pp.
1392-1405.
https://doi.org/10.1007/s12613-024-2871-2
Abstract:
This study investigated the influence of graded Zn content on the evolution of precipitated and iron-rich phases and grain structure of the alloys, designed and developed the Al–8.0Zn–1.5Mg–1.5Cu–0.2Fe (wt%) alloy with high strength and formability. With the increase of Zn content, forming the coupling distribution of multiscale precipitates and iron-rich phases with a reasonable matching ratio and dispersion distribution characteristics is easy. This phenomenon induces the formation of cell-like structures with alternate distribution of coarse and fine grains, and the average plasticity–strain ratio (characterizing the formability) of the pre-aged alloy with a high strength is up to 0.708. Results reveal the evolution and influence mechanisms of multiscale second-phase particles and the corresponding high formability mechanism of the alloys. The developed coupling control process exhibits considerable potential, revealing remarkable improvements in the room temperature formability of high-strength Al–Zn–Mg–Cu alloys.
This study investigated the influence of graded Zn content on the evolution of precipitated and iron-rich phases and grain structure of the alloys, designed and developed the Al–8.0Zn–1.5Mg–1.5Cu–0.2Fe (wt%) alloy with high strength and formability. With the increase of Zn content, forming the coupling distribution of multiscale precipitates and iron-rich phases with a reasonable matching ratio and dispersion distribution characteristics is easy. This phenomenon induces the formation of cell-like structures with alternate distribution of coarse and fine grains, and the average plasticity–strain ratio (characterizing the formability) of the pre-aged alloy with a high strength is up to 0.708. Results reveal the evolution and influence mechanisms of multiscale second-phase particles and the corresponding high formability mechanism of the alloys. The developed coupling control process exhibits considerable potential, revealing remarkable improvements in the room temperature formability of high-strength Al–Zn–Mg–Cu alloys.
2024, vol. 31, no. 6, pp.
1406-1425.
https://doi.org/10.1007/s12613-023-2802-7
Abstract:
With the increasing attention received by lightweight metals, numerous essential fields have increased requirements for magnesium (Mg) alloys with good room-temperature and high-temperature mechanical properties. However, the high-temperature mechanical properties of commonly used commercial Mg alloys, such as AZ91D, deteriorate considerably with increasing temperatures. Over the past several decades, extensive efforts have been devoted to developing heat-resistant Mg alloys. These approaches either inhibit the generation of thermally unstable phases or promote the formation of thermally stable precipitates/phases in matrices through solid solution or precipitation strengthening. In this review, numerous studies are systematically introduced and discussed. Different alloy systems, including those based on Mg–Al, Mg–Zn, and Mg–rare earth, are carefully classified and compared to reveal their mechanical properties and strengthening mechanisms. The emphasis, limitations, and future prospects of these heat-resistant Mg alloys are also pointed out and discussed to develop heat-resistant Mg alloys and broaden their potential application areas in the future.
With the increasing attention received by lightweight metals, numerous essential fields have increased requirements for magnesium (Mg) alloys with good room-temperature and high-temperature mechanical properties. However, the high-temperature mechanical properties of commonly used commercial Mg alloys, such as AZ91D, deteriorate considerably with increasing temperatures. Over the past several decades, extensive efforts have been devoted to developing heat-resistant Mg alloys. These approaches either inhibit the generation of thermally unstable phases or promote the formation of thermally stable precipitates/phases in matrices through solid solution or precipitation strengthening. In this review, numerous studies are systematically introduced and discussed. Different alloy systems, including those based on Mg–Al, Mg–Zn, and Mg–rare earth, are carefully classified and compared to reveal their mechanical properties and strengthening mechanisms. The emphasis, limitations, and future prospects of these heat-resistant Mg alloys are also pointed out and discussed to develop heat-resistant Mg alloys and broaden their potential application areas in the future.
2024, vol. 31, no. 6, pp.
1426-1436.
https://doi.org/10.1007/s12613-023-2809-0
Abstract:
Hot deformation of sintered billets by powder metallurgy (PM) is an effective preparation technique for titanium alloys, which is more significant for high-alloying alloys. In this study, Ti–6.5Al–2Zr–Mo–V (TA15) titanium alloy plates were prepared by cold pressing sintering combined with high-temperature hot rolling. The microstructure and mechanical properties under different process parameters were investigated. Optical microscope, electron backscatter diffraction, and others were applied to characterize the microstructure evolution and mechanical properties strengthening mechanism. The results showed that the chemical compositions were uniformly diffused without segregation during sintering, and the closing of the matrix craters was accelerated by increasing the sintering temperature. The block was hot rolled at 1200°C with an 80% reduction under only two passes without annealing. The strength and elongation of the plate at 20–25°C after solution and aging were 1247 MPa and 14.0%, respectively, which were increased by 24.5% and 40.0%, respectively, compared with the as-sintered alloy at 1300°C. The microstructure was significantly refined by continuous dynamic recrystallization, which was completed by the rotation and dislocation absorption of the substructure surrounded by low-angle grain boundaries. After hot rolling combined with heat treatment, the strength and plasticity of PM-TA15 were significantly improved, which resulted from the dense, uniform, and fine recrystallization structure and the synergistic effect of multiple slip systems.
Hot deformation of sintered billets by powder metallurgy (PM) is an effective preparation technique for titanium alloys, which is more significant for high-alloying alloys. In this study, Ti–6.5Al–2Zr–Mo–V (TA15) titanium alloy plates were prepared by cold pressing sintering combined with high-temperature hot rolling. The microstructure and mechanical properties under different process parameters were investigated. Optical microscope, electron backscatter diffraction, and others were applied to characterize the microstructure evolution and mechanical properties strengthening mechanism. The results showed that the chemical compositions were uniformly diffused without segregation during sintering, and the closing of the matrix craters was accelerated by increasing the sintering temperature. The block was hot rolled at 1200°C with an 80% reduction under only two passes without annealing. The strength and elongation of the plate at 20–25°C after solution and aging were 1247 MPa and 14.0%, respectively, which were increased by 24.5% and 40.0%, respectively, compared with the as-sintered alloy at 1300°C. The microstructure was significantly refined by continuous dynamic recrystallization, which was completed by the rotation and dislocation absorption of the substructure surrounded by low-angle grain boundaries. After hot rolling combined with heat treatment, the strength and plasticity of PM-TA15 were significantly improved, which resulted from the dense, uniform, and fine recrystallization structure and the synergistic effect of multiple slip systems.
2024, vol. 31, no. 6, pp.
1437-1448.
https://doi.org/10.1007/s12613-024-2855-2
Abstract:
Owing to rapid developments in spintronics, spin-based logic devices have emerged as promising tools for next-generation computing technologies. This paper provides a comprehensive review of recent advancements in spin logic devices, particularly focusing on fundamental device concepts rooted in nanomagnets, magnetoresistive random access memory, spin–orbit torques, electric-field modulation, and magnetic domain walls. The operation principles of these devices are comprehensively analyzed, and recent progress in spin logic devices based on negative differential resistance-enhanced anomalous Hall effect is summarized. These devices exhibit reconfigurable logic capabilities and integrate nonvolatile data storage and computing functionalities. For current-driven spin logic devices, negative differential resistance elements are employed to nonlinearly enhance anomalous Hall effect signals from magnetic bits, enabling reconfigurable Boolean logic operations. Besides, voltage-driven spin logic devices employ another type of negative differential resistance element to achieve logic functionalities with excellent cascading ability. By cascading several elementary logic gates, the logic circuit of a full adder can be obtained, and the potential of voltage-driven spin logic devices for implementing complex logic functions can be verified. This review contributes to the understanding of the evolving landscape of spin logic devices and underscores the promising prospects they offer for the future of emerging computing schemes.
Owing to rapid developments in spintronics, spin-based logic devices have emerged as promising tools for next-generation computing technologies. This paper provides a comprehensive review of recent advancements in spin logic devices, particularly focusing on fundamental device concepts rooted in nanomagnets, magnetoresistive random access memory, spin–orbit torques, electric-field modulation, and magnetic domain walls. The operation principles of these devices are comprehensively analyzed, and recent progress in spin logic devices based on negative differential resistance-enhanced anomalous Hall effect is summarized. These devices exhibit reconfigurable logic capabilities and integrate nonvolatile data storage and computing functionalities. For current-driven spin logic devices, negative differential resistance elements are employed to nonlinearly enhance anomalous Hall effect signals from magnetic bits, enabling reconfigurable Boolean logic operations. Besides, voltage-driven spin logic devices employ another type of negative differential resistance element to achieve logic functionalities with excellent cascading ability. By cascading several elementary logic gates, the logic circuit of a full adder can be obtained, and the potential of voltage-driven spin logic devices for implementing complex logic functions can be verified. This review contributes to the understanding of the evolving landscape of spin logic devices and underscores the promising prospects they offer for the future of emerging computing schemes.
Research ArticleOpen Access
2024, vol. 31, no. 6, pp.
1449-1455.
https://doi.org/10.1007/s12613-023-2783-6
Abstract:
A critical challenge to the commercialization of clean and high-efficiency solid oxide fuel cell (SOFC) technology is the insufficient stack lifespan caused by a variety of degradation mechanisms, which are associated with cell components and chemical feedstocks. Cell components related degradation refers to thermal/chemical/electrochemical deterioration of cell materials under operating conditions, whereas the latter regards impurities in feedstocks of oxidant (air) and reductant (fuel). This article provides a thermodynamic perspective on the understanding of the impurities-induced degradation mechanisms in SOFCs. The discussion focuses on using thermodynamic analysis to elucidate poisoning mechanisms in cathodes by impurity species such as Cr, CO2, H2O, and SO2 and in the anode by species such as S (or H2S), SiO2, and P2 (or PH3). The author hopes the presented fundamental insights can provide a theoretical foundation for searching for better technical solutions to address the critical degradation challenges.
A critical challenge to the commercialization of clean and high-efficiency solid oxide fuel cell (SOFC) technology is the insufficient stack lifespan caused by a variety of degradation mechanisms, which are associated with cell components and chemical feedstocks. Cell components related degradation refers to thermal/chemical/electrochemical deterioration of cell materials under operating conditions, whereas the latter regards impurities in feedstocks of oxidant (air) and reductant (fuel). This article provides a thermodynamic perspective on the understanding of the impurities-induced degradation mechanisms in SOFCs. The discussion focuses on using thermodynamic analysis to elucidate poisoning mechanisms in cathodes by impurity species such as Cr, CO2, H2O, and SO2 and in the anode by species such as S (or H2S), SiO2, and P2 (or PH3). The author hopes the presented fundamental insights can provide a theoretical foundation for searching for better technical solutions to address the critical degradation challenges.
2024, vol. 31, no. 6, pp.
1456-1461.
https://doi.org/10.1007/s12613-024-2844-5
Abstract:
Mn2+ doping has been adopted as an efficient approach to regulating the luminescence properties of halide perovskite nanocrystals (NCs). However, it is still difficult to understand the interplay of Mn2+ luminescence and the matrix self-trapped exciton (STE) emission therein. In this study, Mn2+-doped CsCdCl3 NCs are prepared by hot injection, in which CsCdCl3 is selected because of its unique crystal structure suitable for STE emission. The blue emission at 441 nm of undoped CsCdCl3 NCs originates from the defect states in the NCs. Mn2+ doping promotes lattice distortion of CsCdCl3 and generates bright orange-red light emission at 656 nm. The energy transfer from the STEs of CsCdCl3 to the excited levels of the Mn2+ ion is confirmed to be a significant factor in achieving efficient luminescence in CsCdCl3:Mn2+ NCs. This work highlights the crucial role of energy transfer from STEs to Mn2+ dopants in Mn2+-doped halide NCs and lays the groundwork for modifying the luminescence of other metal halide perovskite NCs.
Mn2+ doping has been adopted as an efficient approach to regulating the luminescence properties of halide perovskite nanocrystals (NCs). However, it is still difficult to understand the interplay of Mn2+ luminescence and the matrix self-trapped exciton (STE) emission therein. In this study, Mn2+-doped CsCdCl3 NCs are prepared by hot injection, in which CsCdCl3 is selected because of its unique crystal structure suitable for STE emission. The blue emission at 441 nm of undoped CsCdCl3 NCs originates from the defect states in the NCs. Mn2+ doping promotes lattice distortion of CsCdCl3 and generates bright orange-red light emission at 656 nm. The energy transfer from the STEs of CsCdCl3 to the excited levels of the Mn2+ ion is confirmed to be a significant factor in achieving efficient luminescence in CsCdCl3:Mn2+ NCs. This work highlights the crucial role of energy transfer from STEs to Mn2+ dopants in Mn2+-doped halide NCs and lays the groundwork for modifying the luminescence of other metal halide perovskite NCs.
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