加载路径和温度对NiTi合金相变特性的影响

On the Influence of Loading Path and Temperature on Phase Transition Properties of NiTi Alloy

利用MTS装置,对NiTi形状记忆合金在不同加载路径（拉、压、扭以及拉/压-扭比例加载）和不同温度（28~150℃）下的准静态相变行为进行了较系统的实验研究。结果表明,材料呈现明显的伪弹性效应和拉压不对称性。随着温度的升高,相变起始应力逐渐增大,伪弹性效应和拉压不对称性逐渐减弱。当温度达到一定阈值时,拉压不对称性消失,材料基本呈现弹塑性状态。通过实验曲线确定了NiTi合金的相变临界参数,在σ-τ应力空间中对三种常用宏观相变临界准则进行了讨论,比较了它们各自的适用性。

Systematical experimental study of NiTi shape memory alloy quasi-static phase transition behavior was carried out under different loading path conditions（uniaxial compression and tension,pure torsion and proportional tension/compression-torsion）and at different temperatures ranging from28℃ to 150℃,based on MTS equipment.Experimental results show that the material exhibits apparent pseudo-elastic effect and tension-compression asymmetry.As the temperature increases,the initial phase transition stress increased gradually,meanwhile,the pseudo-elastic effect and tensioncompression asymmetry weaken gradually.When the temperature reaches a certain threshold,the tension-compression asymmetry disappears;NiTi alloy basically presents elastic-plastic behavior.NiTi alloy phase transition critical parameters are determined based on experimental curves.Inσ-τstress plane,three macroscopic phase transition criterions in common use are discussed,and their respective applicability is compared.