|Cite this article as:|
|Jian Rong, Wenlong Xiao, Xinqing Zhao, Chaoli Ma, Haimiao Liao, Donglei He, Ming Chen, Meng Huang, and Chen Huang, A high thermal conductivity and high strength magnesium alloy for high pressure die cast ultrathin-walled component, Int. J. Miner. Metall. Mater.,(2021). https://doi.org/10.1007/s12613-021-2318-y|
With 3C industries developing rapidly, the demand for high-thermal-conductivity magnesium alloy with high mechanical performance is increasing rapidly. However, the thermal conductivities of most common Mg foundry alloys (such as Mg-9wt.%-1wt%Zn) are still relativity low. In the present study, we developed a high-thermal-conductivity Mg-4Al-4Zn-4RE-1Ca (wt.%, AZEX4441) alloy with good mechanical properties for ultrathin-walled cellphone components via high pressure die casting (HPDC). The HPDC AZEX4441 alloy exhibited a fine homogeneous microstructure (the average grain size is 2.8 μm) with granular Al11RE3, fibrous Al2REZn2, and networked Ca6Mg2Zn3 phases distributed at the grain boundaries. The room-temperature thermal conductivity of the HPDC AZEX4441 alloy was 94.4 W/(m·K), which was much higher than 53.7 W/(m·K) of the HPDC AZ91D alloy. The Al and Zn elements of the AZEX4441 alloy were largely consumed by the formation of Al11RE3 and Al2REZn2 as well as Ca2Mg6Zn3 phases due to the addition of RE and Ca. Therefore, the lattice distortion induced by solute atoms of the AZEX4441 alloy (0.171%) was much lower than that of AZ91D alloy (0.441%), which was responsible for the high thermal conductivity of the AZEX4441 alloy. Furthermore, the AZEX4441 alloy exhibited a high yield strength (YS) of ~185 MPa, ultimate tensile strength (UTS) of ~233 MPa, and elongation of ~4.2%, indicating comparable tensile properties to AZ91D alloy. The results will contribute to developing high-performance Mg alloys with a combination of high thermal conductivity, high strength, and good castability.