Microstructure and mechanical properties of cold-rolled Ti_(50)Ni_(47)Fe_3 shape memory alloy  

Ti_(50)Ni_(47)Fe_3形状记忆合金冷轧变形后的组织与性能(英文)

作　　者：李艳锋[1] 康小宇[1] 尹向前[1] 解浩峰[1] 米绪军[1] 

机构地区：[1]北京有色金属研究总院有色金属材料制备加工国家重点实验室,北京100088

出　　处：《Transactions of Nonferrous Metals Society of China》2014年第9期2890-2895,共6页中国有色金属学报（英文版）

基　　金：Project(51201014)supported by the National Natural Science Foundation of China

摘　　要：Mechanical and shape memory properties of a Ti50Ni47Fe3 alloy annealed at 450-750 °C for 1 h after a cold-rolled reduction of 25% were investigated by phase transformation analysis and microstructure characterization using tensile tests, Vickers hardness tests, electrical resistivity-temperature tests, SEM and TEM. From the results of the tensile, it can be inferred that the fracture stress and yield stress decreased and the fracture elongation increased as the annealing temperature increased for the rolled Ti50Ni47Fe3 alloy. They reached stead values when the temperature was above 650 °C. The change in Vickers hardness corresponded to the change in the fracture stress and yield stress. The electrical resistivity-temperature curves suggest that a two- stage martensitic transformation（B2-R-B19′） occurred during cooling and heating. The transformation temperatures decreased to lower temperatures when the annealing temperature was increased and maintained the same after the annealing temperature reached 650 °C. TEM revealed the distinct processes occurring at elevated temperatures： recovery, polygonization, and recrystallization.采用拉伸测试、维氏硬度测试、电阻率-温度曲线测试及扫描电镜和透射电镜观察显微组织的方法研究冷轧变形量为25%的Ti50Ni47Fe3合金经450-750°C下1 h退火后的显微组织和性能。结果表明,冷轧变形增强了合金的抗拉强度和屈服强度,冷轧变形后形成的应力场有助于R相变的发生。随着退火温度的升高,合金的抗拉强度和屈服强度下降,伸长率增大;当退火温度高于650°C时,强度和伸长率趋于稳定。电阻-温度曲线表明,在升、降温过程中发生两阶段相变B2-R-B19′。随着退火温度的升高,合金的相变温度降低;当退火温度高于650°C时,相变温度趋于稳定。随着退火温度的升高,合金依次发生回复、再结晶和晶粒长大。

关 键 词：TiNiFe alloy shape memory alloy cold rolling MICROSTRUCTURE mechanical property 

分 类 号：TG139.6[一般工业技术—材料科学与工程] TG335.12[金属学及工艺—合金]