(湘潭大學(xué) 低維材料及其應(yīng)用技術(shù)教育部重點實驗室，湘潭 411105)
摘 要: 對Ti-7.5Nb-4Mo-2.5Sn形狀記憶合金試樣以及帶有幾何缺陷(中心圓孔和單邊半圓缺口)合金試樣的力學(xué)性能及超彈性能進(jìn)行測試，并采用ARAMIS三維變形分析測試系統(tǒng)對單軸加載-卸載過程中試樣的全場應(yīng)變場分布進(jìn)行實時觀察，研究幾何缺陷對合金應(yīng)變場分布、應(yīng)力誘發(fā)馬氏體相變和超彈性能的影響。結(jié)果表明：在拉伸加載過程中，帶幾何缺陷的試樣在缺陷周圍產(chǎn)生了應(yīng)力集中，導(dǎo)致合金試樣在局部具有較高的應(yīng)變速率和應(yīng)變量；應(yīng)力誘發(fā)馬氏體相變主要受應(yīng)力場分布的影響，而且主要發(fā)生在局部變形帶中。因此，與完整試樣相比，帶幾何缺陷的試樣表現(xiàn)出較高的誘發(fā)馬氏體相變的臨界應(yīng)力和較低的超彈性。
關(guān)鍵字: 鈦基形狀記憶合金；三維變形分析測試系統(tǒng)；幾何缺陷；超彈性
（Key Laboratory of Low Dimensional Materials and Application Technology,
Xiangtan University , Xiangtan 411105，China）
Abstract:The mechanical properties and superelasticity of the Ti-6.5Nb-4Mo-2.5Sn alloy and the samples with a central circular hole and a unilateral semicircular notch, respectively, were evaluated. The full field strain distributions of the samples were monitored during the uni-axis loading-unloading tensile tests by using ARAMIS three-dimensional optical deformation measurement system. The effects of the geometric defects on the strain field, the stress-induced martensite phase transformation and superelasticity were investigated. The results indicate that the samples with geometric defects have the stress concentration closing to the defects on loading, resulting in relatively high strain rate and strain in local zone of alloy. The stress-induced martensite phase transformation is mainly influenced by the strain distributions, and the martensite phase transformation occurs in a localized area. Thus, the samples with the geometry defects exhibit a high critical stress for inducing the martensite transformation and a low superelasticity in comparison with the perfect sample.
Key words: Ti-base shape memory alloy; three-dimensional optical deformation measurement system; geometric defect; superelasticity
