孔缺陷对Ti-7.5Nb-4Mo-2.5Sn形状记忆合金薄板变形行为与超弹性的影响

Effect of pore defects on deformation behavior and superelasticty of Ti-7.5Nb-4Mo-2.5Sn shape memory alloy sheet

对带孔和不带孔的Ti-7.5Nb-4Mo-2.5Sn形状记忆合金薄板试样的超弹性能进行测试,同时利用ARAMIS三维变形分析测试系统对不同合金试样在加载-卸载过程中的应变分布进行实时观测,研究孔径与孔间距对合金应变场分布和超弹性能的影响。结果表明：孔缺陷的引入导致的应力集中会引起试样应变局部化,从而降低合金的超弹性,而且随着孔径的增加和孔间距的减小,应变局部化程度加剧,合金的超弹性也随之降低。

The superelasticity of Ti-7.5 Nb-4 Mo-2.5 Sn alloy sheets with and without pores was evaluated and the full field strain distribution of the samples during the loading-unloading tensile tests was analyzed by using ARAMIS three-dimensional optical deformation measurement system. The effects of pore diameter and pore spacing on the strain field distribution,martensite phase transformation and superelasticity of the alloy were investigated. The results show that the stress concentration caused by the introduction of pore defects will lead to the strain localization of the alloy,thus reducing the superelasticity of the alloy,and with the increasing of pore diameter and the decreaing of the pore spacing,the degree of the strain localization will increase,and the superelasticity of the alloy also decreases.