NiTi形状记忆合金丝在Al基复合材料中的约束态马氏体逆相变特征

摘要

The constrained reverse martensitic transformation characteristicof N iTi shape memory alloy fiber embedded in Al matrix was studied by DSC, XRD and S EM. Results show that two kinds of reverse martensitic transformation appeared in the embedded NiTi fibers after prestrain, those are, the reverse transformat ion of thermal-induced martensite (MT→P) and that of stress-induced martens it e (Md→P). The characteristic temperatures of the reverse transformation of t hermal- induced martensite are very close to that of unprestrained specimens, and are not influenced by prestrain. The characteristic temperatures of the reverse tra n sformation of stress-induced martensite increases with the increasing degree of prestrain. The amount of transformed thermal-and stress-induced martensite d ecreases with the increasing degree of prestrain. The concept of the deformatio n d e gree was introduced in this paper, and the variation of the deformation degree o f stress-induced martensite during the reverse transformation process was discu ssed.%利用DSC，XRD，SEM等实验手段研究了NiTi记忆合金丝在铝基体约束状态下的马氏体逆相变特征。研究结果表明，预应变NiTi记忆合金丝在加热过程中发生两种马氏体逆相变：热致马氏体逆转变(MT→P)与应力诱发马氏体逆转变(Md→P)，其中热致马氏体逆相变温度与未预应变样品基本相同，且不受预应变影响；而应力诱发马氏体向母相转变温度随预应变增加而升高；随预应变增加，热致马氏体与应力诱发马氏体的逆转变量减少。文中引入马氏体变形度概念，并对马氏体在逆转变过程中的变形度变化进行了讨论。