温度与应变率对Cu70Zn30孪晶变形的影响

Effects of strain rate and temperature on deformation twinning in Cu70-Zn30 alloy

为了研究孪晶变形过程中孪晶间距与孪晶片层厚度随温度与应变率变化情况,建立一个关于Cu70-Zn30的流动应力本构方程,其中流动应力分为短程应力与长程应力,短程应力用Johnson-Cook模型描述,长程应力采用幂次强化法则,运用Matlab软件模拟了Cu70-Zn30在不同温度与不同应变率的条件下的孪晶变形,得出了孪晶变形过程中孪晶间距与孪晶片层厚度在不同条件下的演化曲线,通过对比实验结果,证实了低温与高应变率均能促进孪晶变形,其效果随着温度的降低与应变率的升高而增强;相对于应变率的影响,温度的降低更能促使孪晶的生长,孪晶间距的大小与孪晶片层的厚度随着温度的降低与应变率的升高而减小.

Aimed at the evolutions of twin spacing and twin layer thickness on deformation twinning,a flow stress equation of Cu70-Zn30 alloy was proposed.The flow stress of the material was divided into two parts of short-range part and long-range part,the short-range part of the flow stress described by Johnson-Cook equation because of its dependency of temperature and strain rate,the long-range parts adopting the power strengthening law.Deformation twinnings under the different temperatures and different strain rates was simulated by Matlab.Compared with experimental results,it was found low temperature and high strain rate promote deformation twinning;besides,deformation twining is more susceptible to low temperature than high strain rate,and TB spacing and twin layer thickness decrease as the strain rate increases or the temperature drops.