Zr掺杂对Ti-Ni形状记忆合金相变、拉伸性能和循环超弹性的影响

Effects of Zr doping on phase transformation,tensile properties and cyclic superelasticity of Ti-Ni shape memory alloys

为了开发超弹性优异的Ti-Ni基形状记忆合金(SMA),以600℃退火态Ti-50.8Ni和Ti-50.8Ni-0.1Zr(摩尔分数)SMA为研究对象,用示差扫描量热仪、XRD、SEM和拉伸试验研究了Zr掺杂对Ti-Ni基SMA相组成、相变行为、拉伸性能和循环超弹性的影响。结果表明:掺杂0.1%Zr不影响Ti-Ni SMA的组成相和相变类型,但降低马氏体相变温度(t_(M)),增加相变热滞(Δt),提高抗拉强度(R_(m)),降低伸长率(A),增强非线性超弹性稳定性。600℃退火态Ti-50.8Ni和Ti-50.8Ni-0.1Zr合金的室温组成相主要为母相B2,冷却/加热时发生B2→B19′/B19′→B2一步可逆马氏体相变;掺杂0.1%Zr后,Ti-Ni SMA的t_(M)降低了34℃,Δt增加了22℃,R_(m)增加了79 MPa,A降低了22%。随应力-应变循环次数增加,Ti-50.8Ni合金由部分非线性超弹性转变为线性超弹性,Ti-50.8Ni-0.1Zr合金则始终保持稳定非线性超弹性,两种合金的超弹性残余应变(ε_(R))和能量耗散(W_(D))均先降低后趋于稳定。随着循环应变速率的增加,Ti-50.8Ni合金的W_(D)和等效阻尼比先降低后趋于稳定;Ti-50.8Ni-0.1Zr合金的W_(D)和等效阻尼比先升高后趋于稳定。随循环应变幅值的增加,Ti-50.8Ni和Ti-50.8Ni-0.1Zr合金的W_(D)和等效阻尼比皆升高。

In order to develop Ti-Ni base shape memory alloys(SMA)with excellent superelasticity,the effects of Zr doping on the phase composition,phase transformation behavior,tensile properties and cyclic superelasticity of Ti-Ni SMA were investigated by differential scanning calorimetry,XRD,SEM and tensile test,using Ti-50.8Ni and Ti-50.8Ni-0.1Zr(mole fraction,%)SMAs annealed at 600℃ as the research objects.After doping 0.1%Zr,the phase composition and phase transformation type of Ti-Ni SMA are not affected,while the martensitic transformation temperature(t_(M))decreases,the temperature hysteresis(Δt)increases,the tensile strength(R_(m))increases,the percentage elongation(A)decreases,and the stability of cyclic nonlinear superelasticity increases.The main composition phase of Ti-50.8Ni and Ti-50.8Ni-0.1Zr alloys annealed at 600℃is parent phase B2,and B2→B19′/B19′→B2 one-step reversible martensitic transformation occurs upon cooling or heating.After doping 0.1%Zr,the t_(M) decreases by 34℃,theΔt increases by 22℃,the R_(m) increases by 79 MPa,and the A decreases by 22%in Ti-Ni SMA.As the number of stress-strain cycles increases,the Ti-50.8Ni alloy transforms from partial nonlinear superelasticity to linear-like superelasticity,while the Ti-50.8Ni-0.1Zr alloy always presents stable nonlinear superelasticity,and the superelasticity residual strain(ε_(R))and the energy dissipation(W_(D))of the two alloys decrease first and then tend to stable.As the cyclic strain rate increases,the W_(D) and equivalent damping ratio of Ti-50.8Ni alloy decrease first and then tend to stable,the W_(D) and equivalent damping ratio of Ti-50.8Ni-0.1Zr alloy increase first and then tend to stable.As the cyclic strain amplitude increases,the W_(D) and equivalent damping ratio of Ti-50.8Ni and Ti-50.8Ni-0.1Zr alloys all increase.