Cao Shouzhen, Li Zongze, Pu Jiafei, Han Jianchao, Dong Qi, Zhu Mingdong
School of Electrical and Mechanical Engineering, Huangshan University, Huangshan 245021, China.
Engineering Research Center of Advanced Metal Composites Forming Technology and Equipment of Ministry of Education, Taiyuan University of Technology, Taiyuan 030024, China.
Materials (Basel). 2023 Sep 12;16(18):6176. doi: 10.3390/ma16186176.
TiAl alloys are high-temperature structural materials with excellent comprehensive properties, and their ideal service temperature range is about 700-950 °C. High-Nb containing the Ti-46Al-8Nb-2.5V alloy was subjected to hot compression and subsequent annealing at 900 °C. During hot compression, work-hardening and strain-softening occurred. The peak stresses during compression are positively correlated with the compressive strain rates and negatively correlated with the compression temperatures. The α phase exhibited a typical (0001)α basal plane texture after hot compression, while the β and γ phases did not show a typical strong texture. Subsequent annealing at 900 °C of the hot-compressed samples resulted in significant phase transformations, specifically the α → γ and β → γ phase transformations. After 30 min of annealing, the volume fraction of the α phase decreased from 39.0% to 4.6%. The microstructure characteristics and phase fraction after 60 min of annealing were similar to those after 30 min. According to the calculation of Miller indexes and texture evolution during annealing, the α → γ phase transformation did not follow the Blackburn orientation relationship. Multiple crystal-oriented α phases with nanoscale widths (20~100 nm) precipitate within the γ phase during the annealing process, which means the occurrence of γ → α phase transformation. Still, the γ → α phase transformation follows the Blackburn orientation relationship.
TiAl合金是具有优异综合性能的高温结构材料，其理想服役温度范围约为700 - 950°C。对含高Nb的Ti-46Al-8Nb-2.5V合金进行热压缩并随后在900°C退火。在热压缩过程中，发生了加工硬化和应变软化。压缩过程中的峰值应力与压缩应变速率呈正相关，与压缩温度呈负相关。热压缩后α相呈现典型的(0001)α基面织构，而β相和γ相未呈现典型的强织构。对热压缩后的样品在900°C进行后续退火导致了显著的相变，具体为α→γ和β→γ相变。退火30分钟后，α相的体积分数从39.0%降至4.6%。退火60分钟后的微观结构特征和相分数与30分钟后的相似。根据米勒指数计算和退火过程中的织构演变，α→γ相变不遵循布莱克本取向关系。在退火过程中，纳米级宽度（20~100nm）的多晶取向α相在γ相内析出，这意味着发生了γ→α相变。不过，γ→α相变遵循布莱克本取向关系。
