新型无镍β型钛合金超弹性的研究

Study on super-elasticity of new β-type titanium alloys without Ni

采用钛合金d电子理论设计超弹性钛合金。采用水冷铜坩埚电弧熔炼的方法制备铸锭,经均匀化、冷轧和退火处理后,使用XRD和TEM分析退火后合金相组成,使用U型法测试超弹性。结果表明,Ti-24Nb-4Zr合金经800℃退火后具有优良的超弹性,U型法测试加载3.76%应变在卸载后可以完全回复。Sn具有强烈降低Ms点的作用,使得Ti-24Nb-2Zr-2Sn合金获得稳定的室温β相。300℃退火生成的ω相能够避免塑性变形过早发生,提高Ti-24Nb-2Zr合金的超弹性。但其同样阻碍β相的应力诱发马氏体转变,使得Ti-24Nb-4Zr合金经300℃退火获得的超弹性低于800℃退火获得的结果。

Titanium alloys with super-elasticity were designed by d-electron alloy design theory.Ti-Nb-Zr and Ti-Nb-Zr-Sn alloy ingots were arc-melted in a water-sealed copper crucible.Then,the ingots were homogenized,cold rolled and finally annealed.Phase constitution of the annealed alloys was analyzed by utilizing X-ray diffraction（XRD） scanning electron microscopy（SEM） and transmission electron microscopy（TEM）.The super-elasticity of the alloys was measured by U bending tests.Ti-24Nb-4Zr alloy show,excellent super-elasticity that fully recovery is obtained in U bending test with applied strain of 3.76%.The addition of Sn can strongly reduce Ms temperature,so that stable β phase is obtained at room temperature in Ti-24Nb-2Zr-2Sn alloy.The ω phase,which forms during annealing at 300 ℃,can restrain plastic deformation occurring,thus super-elasticity of Ti-24Nb-2Zr alloy increases.Meanwhile,it hinders stress-induced martensite transformation.This effect causes that Ti-24Nb-4Zr alloy annealed at 300 ℃ shows lower super-elasticity than the alloy after annealing at 800 ℃.