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中国有色金属学报

ZHONGGUO YOUSEJINSHU XUEBAO

第30卷    第8期    总第257期    2020年8月

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文章编号:1004-0609(2020)-08-1802-09
时效温度对Ti-50.8Ni-0.1Nb合金相变和形状记忆行为的影响
刘康凯,贺志荣,冯 辉,杜雨青,冀荣耀

(陕西理工大学 材料科学与工程学院,汉中 723001)

摘 要: 采用X射线衍射仪、示差扫描量热仪、激光扫描共聚焦显微镜、TEM和拉伸实验研究了时效温度(tag)对(300,400,500,600 ℃;1 h)时效态Ti-50.8Ni-0.1Nb形状记忆合金相变、组织和形状记忆行为的影响。结果表明:300~600 ℃时效态Ti-50.8Ni-0.1Nb合金的相组成为B2和B19′。随tag升高,合金冷却/加热相变类型发生由A→R→M/M→R→A型向A→M/M→A型转变(A—母相B2,CsCl结构;R—R相,菱方结构;M—马氏体相B19′,单斜结构),R相变温度先升高后降低,M相变温度先降低后升高再降低;R和M相变热滞分别在3.8~12.0 ℃和8.7~131.7 ℃之间变化。随tag升高,合金中Ti3Ni4析出相的形态发生由点状→针状→透镜状→片状转变。400、 500 ℃时效态合金的抗拉强度高于300、600 ℃时效态合金的,其伸长率则低于后者。300、400、600 ℃时效态合金呈超弹性,500 ℃时效态合金呈形状记忆效应。随应力-应变循环次数增加,合金的应力-应变曲线平台应力下降并趋稳,300、400 ℃时效态合金的超弹性稳定性良好。

 

关键词: Ti-50.8Ni-0.1Nb合金;形状记忆合金;时效温度;相变;形状记忆行为

Effect of aging temperature on phase transformation and shape memory behaviors of Ti-50.8Ni-0.1Nb alloy
LIU Kang-kai, HE Zhi-rong, FENG Hui, DU Yu-qing, JI Rong-yao

School of Materials Science and Engineering, Shaanxi University of Technology, Hanzhong 723001, China

Abstract:The effect of aging temperature (tag) on the phase transformation, microstructure, and shape memory behaviors of Ti-50.8Ni-0.1Nb shape memory alloy aged at 300, 400, 500 and 600 ℃ for 1 h, respectively, were investigated by means of X-ray diffractometry, differential scanning calorimetry, laser scanning confocal microscope, TEM and tensile test. The results show that the phase compositions of Ti-50.8Ni-0.1Nb alloy aged at 300-600 ℃ are B2 and B19′. With increasing tag, the transformation types of the alloy change from A→R→M/M→R→A to A→M/M→A (A—parent phase B2, CsCl; R—R phase, rhombohedral; M—martensite B19′, monoclinic) upon cooling/heating; the R phase transition temperature increases first and then decreases, and the M transition temperature decreases first, then increases and then decreases; the R and M temperature hysteresis change in the range of 3.8-12.0 ℃ and 8.7-131.7 ℃, respectively. With increasing tag, the morphology of Ti3Ni4 precipitates in the alloy changes from granular → acicular → lenticular → flaky. The tensile strength of the alloy aged at 400 ℃ and 500 ℃ is higher than that of the alloy aged at 300 ℃ and 600 ℃, while the percentage elongation of the former is lower than that of the latter. The alloys aged at 300, 400, 600 ℃ show superelasticity, and the alloy annealed at 500 ℃ shows shape memory effect. With increasing stress-strain cycling number, the platform stress in the stress-strain curve of the alloy decreases. The stability of the superelasticity in the alloy aged at 300 ℃ and 400 ℃ is excellent.

 

Key words: Ti-50.8Ni-0.1Nb alloy; shape memory alloy; aging temperature; phase transformation; shape memory behavior

ISSN 1004-0609
CN 43-1238/TG
CODEN: ZYJXFK

ISSN 1003-6326
CN 43-1239/TG
CODEN: TNMCEW

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