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Ying Gao, Ce Zhang, Jiazhen Zhang, and Xin Lu, Microstructure evolution and strengthening mechanism of high-performance powder metallurgy TA15 titanium alloy by hot rolling, Int. J. Miner. Metall. Mater., 31(2024), No. 6, pp.1426-1436. https://dx.doi.org/10.1007/s12613-023-2809-0
Ying Gao, Ce Zhang, Jiazhen Zhang, and Xin Lu, Microstructure evolution and strengthening mechanism of high-performance powder metallurgy TA15 titanium alloy by hot rolling, Int. J. Miner. Metall. Mater., 31(2024), No. 6, pp.1426-1436. https://dx.doi.org/10.1007/s12613-023-2809-0
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高性能粉末冶金TA15钛合金热轧制组织演变与强化机理

摘要: 利用粉末冶金烧结坯进行热变形是制备钛合金加工材的有效技术之一,对高合金化钛合金来讲其优势更为显著。本研究以元素粉末为原料,采用粉末冶金冷压烧结结合高温热轧制备了Ti–6.5Al–2Zr–Mo–V(TA15)钛合金板,探究了不同工艺参数下合金的微观组织结构与力学性能,并利用OM、EBSD等对合金组织演变与力学性能强化机理进行了分析。结果显示,合金在烧结过程中化学成分扩散均匀无偏析,提高烧结温度加速了基体孔洞的闭合;在1200°C下2个道次80%形变量的热轧制及固溶时效后,所得钛合金板材的室温抗拉强度与延伸率分别为1247 MPa、14.0%,与烧结坯相比分别增加了24.5%及40.0%;合金的组织因连续动态再结晶显著细化,被低角度晶界包围的亚结构旋转并吸收位错使得再结晶得以完成;热轧结合热处理后合金的强度与塑性协同提高,这源于热处理后致密且均匀、细小的再结晶组织,高温下热轧制的完成源于多滑移系的协同作用。

 

Microstructure evolution and strengthening mechanism of high-performance powder metallurgy TA15 titanium alloy by hot rolling

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.

 

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