Ti-47Al-2Cr-0.2Mo合金多道次热塑性变形行为

Multi-stage plastic deformation behavior of TiAl-based alloy at high temperature

采用Gleeble-1500热模拟实验机及光学显微镜和透射电子显微镜研究了Ti-47Al-2Cr-0.2Mo(原子分数,%)合金在2.5 s-1,1050～1150℃,道次保温时间分别为1 min、5 min、10 min条件下的多道次热压缩变形行为及其组织演化规律。结果表明,增大道次变形量,合金软化率增大;随着道次间保温时间的延长,合金软化率逐渐增大;变形及保温温度升高,合金软化率提高。动态和亚动态再结晶是合金发生软化的主要原因。再结晶优先发生于层片晶团边界处。随着变形温度升高,γ晶粒内的孪生增多。经过热压缩变形后,组织被细化和均匀化。位错和孪生是主要的变形机制。

Hot deformation behavior of Ti-47Al-2Cr-0.2Mo（at%） alloy were studied on a Gleeble-1500 machine at 1000-1150 ℃ with the strain rate of 2.5 s-1.Multi-stage compression tests of the alloy specimens were conducted with intervals of 1 min,5 min and 10 min,respectively,between two-stage compression.Microstructure evolution of the alloy during deformation was investigated by optical microscopy and transmission electron microscopy.The results show that static softening in the intervals increases with increasing deformation of per-pass,interval time and deforming temperature.For the test alloy,dynamic recrystallization and meta-dynamic recrystallization may play an important role in the softening.In general,the dynamic recrystallization（DRX） prefers to initiate at triple junctions of lamellae,and twins in γ grains increase with the increasing of deformation temperature.After hot compression,the microstructure of the alloy is refined and homogenized obviously.It is demonstrated that twinning and dislocations are the primary deformation mechanisms during compression.