形变退火态Ti-50.8Ni-0.1Nb合金的相变和形状记忆行为  

Transformation and shape memory behaviors of deformed and annealed Ti-50.8Ni-0.1Nb alloy

作　　者：贺志荣[1] 刘康凯[1] 王芳[2] 冯辉[1] 杜雨青 HE Zhi-rong;LIU Kang-kai;WANG Fang;FENG Hui;DU Yu-qing(School of Materials Science and Engineering, Shaanxi University of Technology, Hanzhong 723001, China;Library, Shaanxi University of Technology, Hanzhong 723003, China)

机构地区：[1]陕西理工大学材料科学与工程学院,汉中723001 [2]陕西理工大学图书馆,汉中723003

出　　处：《中国有色金属学报》2019年第4期742-748,共7页The Chinese Journal of Nonferrous Metals

基　　金：国家重点研发计划项目(2016YFE0111400);陕西省重大科技创新项目(2017ZKC04-84);汉中市科技计划项目(HZGXW1602);陕西理工大学研究生创新基金项目(SLGYCX1823)~~

摘　　要：用XRD、光学显微镜、示差扫描量热仪和拉伸实验研究退火温度(t_a)对冷拉Ti-50.8Ni-0.1Nb(摩尔分数,%)合金组织、相变和形状记忆行为的影响。结果表明:350～700℃退火态Ti-50.8Ni-0.1Nb合金由马氏体M(B19′,单斜结构)和母相A(B2,Cs Cl型结构)组成。随t_a升高,合金组织形貌由纤维状变为等轴状,再结晶温度约为580℃;合金冷却/加热相变类型由A→R→M/M→R→A型向A→R→M/M→A型向A→M/M→A型转变(R-R相,菱方结构),R相变温度降低,M相变温度和热滞先升高后降低,R相变热滞为6.7～9.8℃。350～550℃退火态合金的抗拉强度高于600～700℃退火态合金的,伸长率则远低于后者的。400～550℃退火态合金呈形状记忆效应,350℃退火态和600℃及以上温度退火态合金呈超弹性。随应力-应变循环次数增加,合金应力-应变曲线的平台应力下降。400～550℃退火态合金的形状记忆效应和600℃及以上温度退火态合金的超弹性稳定性良好。The effects of annealing temperature (Ta) on the microstructure, phase transformation and shape memory behavior of cold drawing Ti-50.8Ni-0.1Nb (mole fraction,%) shape memory alloy were investigated by XRD, optical microscopy, differential scanning calorimetry and tensile test. The results show that the phase compositions of Ti-50.8Ni-0.1Nb alloy annealed at 350-700 ℃ are martensite M (B19′, monoclinic) and parent phase A (B2, CsCl). With increasing Ta, the microstructure morphology of the alloy changes from fibrous to equiaxed grain, the recrystallization temperature is about 580 ℃;the transformation types of the alloy change from A→R→M/M→R→A to A→R→M/M→A to A→M/M→A (A-parent phase B2, CsCl;R-R phase, rhombohedral;M-martensite B19′, monoclinic) upon cooling/heating, the R transformation temperature of the alloy decreases, the M transformation temperature and temperature hysteresis increases firstly and then decreases, the R transformation temperature hysteresis is 6.7-9.8 ℃. The tensile strength of the alloy annealed at 350-550 ℃ is higher than that of the alloy annealed at 600-700 ℃, while the percentage elongation of the former is lower than that of the latter. The alloy annealed at 400-550 ℃ shows shape memory effect, and the alloys annealed at 300 ℃ and 600-700 ℃ show superelasticity. With increasing stress-strain cycling number, the platform stress in the stress-strain curve of the alloy decreases. The stability of the shape memory effect in the alloy annealed at 400-550 ℃ and the superelasticity in the alloy annealed at 600-700 ℃ are well.

关 键 词：Ti-Ni-Nb合金 形状记忆合金 退火 相变 形状记忆行为 

分 类 号：TG113.25[金属学及工艺—物理冶金]