置氢TC21合金粉末烧结材料高温流变行为及组织演变

采用热压缩试验研究置氢量0.22wt%TC21钛合金粉末烧结材料在温度850℃~1000℃和应变速率0.001s-1~0.10 s-1范围内的流变行为和组织演变,分析了该合金烧结材料在试验参数范围内变形的应力-应变曲线特征。动力学分析获得置氢TC21合金粉末烧结材料高温压缩变形的应力指数和变形激活能分别为3.32kJ/mol和442.74kJ/mol,表明置氢TC21合金粉末制品在高温变形过程中均发生了动态再结晶。组织观察发现,在β相区变形时,β晶粒随金属流动方向明显被拉长、变形;在α+β相区变形时,β相的组织变化基本同其在β相区变形时一样,只是β相再结晶过程加剧;在α相区变形时,原始的的片状和等轴状组织中α相组织发生再结晶,初生的α相含量逐渐减少。平面应变状态下发生动态再结晶的临界变形量大于均匀单向压缩状态下的临界变形量。

Hot deformation behavior and microstructure evolution of sintered TC21 alloy using hydrogenated powder

The hot deformation behavior and microstructure evolution of TC21 alloy by die forming and sintering using hydrogena-ted powder with hydrogen content of 0. 22wt % structure were studied in the temperature range 850℃～1000℃ and strain rate range 0. 001s~(-1) ～0. 1s~(-1) by hot compression tests. Characteristics of stress strain curves of the alloy deformed with the test parameters were analyzed. Kinetics analyses indicate that the stress exponent and deforming activation energy were 3. 32kJ×mol~(-1) and 442. 74kJ×mol~(-1) respectively, which indicate that dynamic recrystallization occurred. Microstructure observation indicates that the β grains was elongated along metal flowed with deformation in β region, the same microstructure change of β phase as β region besides recrystallization aggravated in α+β region deformation, it take place recrystallization of α phase original lamellar and equiaxed structure which the mass fraction of primary α phase content showed a decreasing trend. The dynamic recrystallization critical deformation in plane strain state of the TC21 sintered body were more than in upsetting deformation state.