稀土元素Ce对Ti-Ni形状记忆合金力学性能的影响

Effect of rare earth Ce addition on mechanical properties of Ti-Ni shape memory alloys

采用拉伸试验研究了稀土元素Ce对Ti-Ni合金力学性能的影响,通过扫描电镜对Ti-Ni-Ce合金的断口形貌进行观察。实验结果表明,添加稀土元素Ce使Ti-Ni合金的应力—应变行为有显著影响。在马氏体状态拉伸时,当x(Ce)低于0.5%时,合金的应力—应变曲线出现明显的屈服平台;而当x(Ce)超过1%时,合金的应力—应变曲线上无明显的屈服平台,以连续屈服和强烈的加工硬化为特征。随Ce加入量增加,合金的延伸率降低、脆性增大,断裂类型由微孔聚集型的韧性断裂逐渐转变为沿晶脆性断裂。因此,Ce的加入量不能超过1%,否则将损害Ti-Ni合金的使用性能。

This paper presents the study of effect of Ce addition on the mechanical properties of Ti - Ni（x（ Ni）50.7% ） alloy by tensile tests and investigation into the fracture morphology of Ti -Ni -Ce alloys by SEM in the paper. The results show that Ce addition gives an evident effect on the stress-strain curves of Ti - Ni alloys. When the alloys are subjected to tension under martensitic state, the stress-strain curve of Ti - Ni alloy with 0. 5 % x （Ce） or less gives evident stress plateau ; the tensile stress-strain curve of Ti -Ni alloy containing 1% x（Ce） or more shows no evident stress plateau and the stress-strain curve is characterized by continuous yielding and high work hardening. Increase of Ce content leads to the elongation decreases and the brittleness increases. Increasing Ce content results in gradual changes from ductile rupture to brittle one in the fracture type of Ti - Ni - Ce alloys. Ce addition of more than 1% is likely damage the performance of Ti -Ni alloys.