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
王涛涛 1武泽园 1李亚鹏 1廖仲尼 1王永善1
作者信息
- 1. 陕西理工大学材料科学与工程学院,陕西 汉中 723001
- 折叠
摘要
通过对Ni50.2 Ti49.8(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.
Abstract
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 Ti49.8 Ni50.2(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 coarse-grained 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Key words
nanocrystalline/NiTi/memory alloy/R phase/superelastic stability引用本文复制引用
基金项目
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(209020369)
出版年
2024
NETL
NSTL
万方数据