纳米晶NiTi记忆合金应力诱发R→B19′相变的超弹稳定性  

Superelastic stability of stress induced R→B19′transformation in nanocrystalline NiTi memory alloy

作　　者：王涛涛 武泽园 李亚鹏[1] 廖仲尼 王永善[1] WANG Tao-tao;WU Ze-yuan;LI Ya-peng;LIAO Zhong-ni;WANG Yong-shan(School of Materials Science and Engineering,Shaanxi University of Technology,Hanzhong 723001,China)

机构地区：[1]陕西理工大学材料科学与工程学院,陕西汉中723001

出　　处：《材料热处理学报》2024年第5期94-99,共6页Transactions of Materials and Heat Treatment

基　　金：陕西省自然科学基础研究计划一般项目(2024JC-YBQN-0366);陕西理工大学人才启动科研基金资助项目(209020369)。

摘　　要：通过对Ni_(50.2)Ti_(49.8)(at%)记忆合金丝材进行大变形冷拔和低温退火获得了平均晶粒尺寸为15 nm的纳米晶NiTi记忆合金丝材样品,然后采用应变量为6%的20次拉伸循环实验研究了纳米晶NiTi合金力致R→B19′相变的超弹稳定性。结果表明:纳米晶NiTi合金在经过20次拉伸循环变形后,其超弹应力为734 MPa,超弹应力的减小率为16%,残余应变为0.61%,此综合超弹性能优于以往粗晶NiTi记忆合金。这主要源于纳米晶NiTi记忆合金中细晶强化显著提高了合金屈服强度,因此降低合金马氏体相变过程中塑性变形,可使纳米晶NiTi记忆合金呈现高的超弹稳定性。A nanocrystalline NiTi memory alloy wire sample with an average grain size of 15 nm was obtained by large deformation cold drawing and low temperature annealing of Ti_(49.8)Ni_(50.2)(at%)memory alloy wire.Then,20 tensile cycles experiments with a strain of 6% were used to study the superelastic stability of the nanocrystalline NiTi alloy during stress-induced R→B19′transformation.The results show that after 20 cycles of tensile deformation,the superelastic stress of the nanocrystalline NiTi alloy is 734 MPa,the reduction rate of superelastic stress is 16%,and the residual strain is 0.61%.This comprehensive superelastic performance is superior to previous coarsegrained NiTi memory alloys.This is mainly due to the significant increase in yield strength of the nanocrystalline NiTi memory alloy due to fine grain strengthening,thus reducing plastic deformation during martensitic transformation of the alloy and enabling the nanocrystalline NiTi memory alloy to exhibit high superelastic stability.

关 键 词：纳米晶 NITI 记忆合金 R相 超弹稳定性 

分 类 号：TG139.6[一般工业技术—材料科学与工程]