Fe-27Mn-6Si-5Cr 形状记忆合金丝材退火对显微组织与相变点的影响

Effect of Annealing on Microstructure and Transformation Temperature of Fe 27Mn 6Si 5Cr Shape Memory Alloy Wire

对Ｆｅ－２７Ｍｎ－６Ｓｉ－５Ｃｒ（％，质量分数）形状记忆合金热拉丝经不同温度退火，观察其显微组织．发现７００°Ｃ时再结晶刚结束，此时晶粒最细小；低于７００°Ｃ退火，试样内存在变形晶粒；８００°Ｃ退火再结晶，呈现晶粒粗大．采用膨胀法和四端电阻法研究退火温度对试样热诱发ε－马氏体Ｍｓ的影响．Ｍｓ随退火温度的升高而升高，到７００°Ｃ达到最高，８００°Ｃ以上Ｍｓ复又降低，这可能与７００°Ｃ退火后变形结构的消除、再结晶晶粒十分细小和层错单一取向形成有关．

It is found from the SEM microstructure analysis under different annealing temperature that the recrystallization temperature of the hot drawing wire of Fe 27Mn 6Si 5Cr shape memory alloy is about 700℃. Deformation grains are existed in the specimens when the annealing temperature is below 700℃; while above 700℃, the grains become coarse. In this study, the thermal dilation method and resistivity method are used to investigate the effect of annealing temperature on the thermal induced ε martensitic transformation point M s. The results show that M s rises with the increasing of the annealing temperature and reaches the highest point at 700℃, then decreases above 700℃. The phenomenon may be due to the elimination of the deformed structure, the small recrystallization grain size and the formation of the stacking faults along a single orientation.