退火态Ti-49.8Ni形状记忆合金的组织及性能研究

用光学显微技术及拉伸试验研究了退火温度T_a和形变温度T_d对Ti-49.8Ni(原子分数,%)形状记忆合金(SMA)丝材及弹簧的显微组织与形状记忆行为的影响.结果表明:冷加工态Ti-49.8Ni合金组织呈纤维状;退火后,随T_a升高,其显微组织逐渐从纤维状向等轴状过渡,合金丝和弹簧的马氏体(M)再取向力先减小后增大;退火态合金在室温下呈形状记忆效应,随T_d升高,合金的M再取向力升高,形状记忆效应份额逐渐减少,超弹性效应份额逐渐增加.

Study on Microstructure and Properties of Ti-49.8Ni Shape Memory Alloy As-annealed

The effects of annealing temperature (T_a) and deforming temperature (T_d) on the microstructure and shape memory behavior of Ti-49.8Ni shape memory alloy wires and springs were investigated by optical micrometry and tensile test. The results show that the microstructure of cold-worked Ti-Ni alloy is fibroid. After annealing, the microstructure of the alloy is gradually changing from fibroid to equi-axed grain, and the martensite reoriented stress of the alloy wires and springs decreases first and then increases with the annealing temperature increasing. The annealed alloy shows shape memory effect at room temperature. With the deforming temperature increasing, the martensite reoriented stress increases, the portion of shape memory effect decrease and that of superelasticity increase gradually.