固溶-时效处理对Ti-Ni-Cr形状记忆合金拉伸性能和显微组织的影响

Effects of Solution Annealing and Aging on Tensile Property and Microstructure of Ti-Ni-Cr Shape Memory Alloy

用拉伸试验和透射电子显微镜研究了固溶时效处理对Ti-50.8Ni-0.3Cr形状记忆合金拉伸性能和显微组织的影响。800℃固溶淬火态合金的塑性优于时效态。随时效时间tag延长,300和400℃时效态合金的抗拉强度Rm300和Rm400先急剧增大后趋于稳定。

Effects of solution annealing and aging on tensile property and microstructure of Ti-50.8Ni-0.3Cr shape memory alloy were investigated by tensile test and transmission electron microcopy. The plasticity of 800℃ solution annealed alloy is better than that of aged alloy. With increasing of the aging time tag, the tensile strengths Rm300 and Rm400 of 300 and 400 ℃ aged alloys increase sharply firstly and then tend to stabilizing, and Rm300 〈 Rm400; the elongation A300 and A400 decrease sharply firstly and then tend to stabilizing. After aging at 500℃, the Rm500 decreases sharply firstly and then tend to stabilizing, the A500 increases sharply firstly and then tend to stabilizing. With increasing of tag, the critical stresses of inducing Martensitic transformation RM300 and RM400 for 300 and 400℃ aged alloys decrease gradually, while RM500 firstly decreases, then sharply increases, at last decrease gradually again, and the maximum of RM500 is reached at tag=5-10 h. Furthermore, with increasing of tag, the morphology of Ti3Ni4 precipitates of 300℃ aged alloy displays fine particle dispersed microstructure; the morphology of Ti3Ni4 precipitates of 400℃ aged alloy evolves from particle shape to the lenticular; the morphology of Ti3Ni4 precipitates of 500℃ aged alloy evolves from lenticular shape to needle to plate shape. The influence of the aging temperature on the morphology of Ti3Ni4 precipitates is more significant than that of the aging time.