冷变形和中温处理对TiNiCr形状记忆合金相变的影响

Effect of Cold-deformation and Mid-temperature Treatment on Phase Transformation of TiNiCr Shape Memory Alloys

以TiNiCr形状记忆合金为研究对象,着重研究了不同的预变形、中温处理对该形状记忆合金相变的影响,通过示差扫描量热实验和金相组织照片的观察,研究了不同的预变形、中温处理对TiNiCr形状记忆合金的DSC曲线以及相变点的影响。实验表明:马氏体相转变温度Ms随着冷变形量的增加先升高,当预变形超过15%后,相变点Ms随预变形量的增加而降低;As,Af在预变形量为15%时达到最大,热处理能显著提高马氏体相变温度,使得相变更容易进行,460℃中温处理使TiNiCr合金Ms增幅较大,而随着热处理温度的继续增加,Ms差距变小;在400℃中温处理下,保温时间越长,Ms,Mf温度降低越明显。而热滞As-Ms几乎不受中温处理时间的影响。

The effect of cold-deformation and mid-temperature treatment on the phase transformation behaviors of TiNiCr SMA（shape memory alloys） have been comparatively investigated.The effect of different cold-deformation and mid-temperature treatment on the DSC curve and phase transformation point of TiNiCr shape memory alloys have been researched by differential scanning calorimeter（DSC） and observation of metallographic microstructure photographs.The results show that martensitic transition temperature Ms would rise as the cold-deformation increased until that the cold-deformation increased more than 15%,then the Ms is reducing with the the cold-deformation increasing.As and Af reached the peak point when the cold-deformation is up to 15%.The martensitic transformation temperature can be significantly improved by heat-treatment which made phase transformation easily.The Ms increasing rate is remarkably increased after heating at 460℃ and decreased with mid-temperature treatment increasing.Under the heat treatment temperature of 400℃,the Ms and Mf will decrease more remarkably as the more time is keeping.The thermal hysteresis As-Ms is not affected by the time of mid-temperature treatment.