高应变率下Ni-Ti合金力学性能及微观组织研究

Research on Mechanical Properties and the Microstructure of Ni-Ti alloy under high strain rate

摘要:

摘 要: 利用INSTRON5985电子万能试验机和分离式Hankinson压杆冲击加载装置对Ni-Ti形状记忆合金棒材进行准静态和动态力学性能研究，并通过XRD、光学显微镜、SEM等微观分析方法对不同状态下的微观组织结构进行分析。结果表明：Ni-Ti合金原始组织存在B2奥氏体相、B19’马氏体相、Ni3Ti4相，晶粒细小且呈等轴分布；准静态压缩和动态压缩均发生应力诱发马氏体相变，但动态压缩应力-应变曲线无屈服平台出现，存在应变率硬化效应；在一定的应变率范围内，随着应变率的提高，晶粒内条纹状组织增多，应力诱发马氏体相变程度增大。

Abstract:

Abstract:Quasi-static and dynamic mechanical properties of Ni-Ti shape memory alloy bar have been investigated by using electronic universal testing machine (INSTRON5985) and Split-Hopkinson Pressure Bar (SHPB), and analyze the microstructure under different condition through microscopic analysis methods such as XRD, OM and SEM. The experimental results show that Ni-Ti alloy original organizations consist of B2 austenitic phase, B19’ martensite phase , Ni3Ti4 phase and with small equiaxed grains; quasi-static and dynamic compression all occur stress induced martensite phase transformation, but dynamic compression stress-strain curve does not appear yield platform and presents strain rate hardening effect; within a certain range of strain rate, the striped organizations increase with the increase of strain rate, and the degree of stress induced martensite phase transformation increases.