【摘要】 采用SHPB技术和可控速率循环加温条件下变形恢复量测定装置研究了冲击及静载变形后的TiNi形状记忆合金的单程及双程形状记忆特性。发现马氏体状态下的TiNi合金的力学特性显示出明显的应变率强化效应 ,并且高应变率压缩应力应变曲线呈现流动平台。应变率对形状记忆效应的影响具有双重性 ,当外加应力或残余应变较小 ,可逆非弹性变形机制起主导作用时 ,提高应变率可以增加其单程形状记忆效应 ;而随外加应力或残余应变增大 ,当基于位错机制的不可逆非弹性变形机制起主导作用时 ,应变率提高却抑制了其单程形状记忆效应。应变率对TiNi合金双程形状记忆效应的影响视塑性变形的大小而异 ,高应变率动载后的双程形状记忆效应在较小塑性应变时 ,比静载后的要强 ;但在较大塑性应变时两者差别不大更多还原

【Abstract】 Using split Hopkinson bar technique,the dynamic stress strain character and the rate dependent shape memory effect of TiNi alloy were studied.It was shown that the mechanical behavior of TiNi alloy with martensitic phase displays a marked strain rate strengthening effect,and a flow plateau was observed on the stress strain curve at high strain rate.The experimental results reveal a dual nature of the dependence of shape memory effect upon strain rate.If the stress or residual strain is low,when the reversible inelastic deformation mechanism plays a dominant role,the increase of strain rate enhances the one way shape memory effect for TiNi SMA;but while the stress or residual strain is larger and the non reversible inelastic deformation plays a leading role,the increase of strain rate,on the contrary,suppresses the one way shape memory effect.The influence of strain rate on the two way shape memory effect for TiNi SMA is related to its plastic deformation.At smaller plastic strain,the two way shape memory effect of impacted specimen is larger than that of statically loaded specimen;but at larger plastic deformation,no marked difference between them was observed.更多还原