Al-5Zn-2Mg合金在动态回复过程中的流变软化与微观组织演变(英文)

将7005铝合金在变形温度为300~500°C、应变速率为0.05~50 s-1的条件下进行等温压缩实验,研究材料的流变应力行为及微观组织演变规律,使用金相显微镜(OM)、透射电子显微镜(TEM)、电子背散射花样(EBSD)等方法观察、分析热压缩试样。通过计算得到7005铝合金的激活能为147 kJ/mol,与纯铝的晶格自扩散能(142kJ/mol)相近。7005铝合金热变形过程中主要的恢复机制为动态回复。在高应变速率(50 s-1)条件下,试样由于变形温升的影响会发生流变软化。经过温升修正后,在较高变形温度下材料依然存在软化现象。通过微观组织分析可知,该现象主要与材料动态回复过程中晶界迁移引起的晶粒粗化有关。

Flow softening behavior and microstructure evolution of Al-5Zn-2Mg aluminum alloy during dynamic recovery

The flow stress behavior and microstructure development of Al-5Zn-2Mg （7005） aluminum alloy were studied by hot compression tests at deformation temperatures between 300-500 ＆#176;C and strain rates between 0.05-50 s-1. The deformed structures of the samples were observed by optical microscopy （OM）, transmission electron microscopy （TEM） and electron backscattering diffraction （EBSD） analysis. The calculated activation energy is 147 kJ/mol, which is very close to the activation energy for lattice self-diffusion in aluminum （142 kJ/mol）. Dynamic recovery is the dominant restoration mechanism during the deformation. At high strain rate of 50 s-1, temperature rise due to deformation heating leads to a significant flow softening. Microstructure observations indicated that the remaining softening after deformation heating correction at high strain rate and the softening observed at high temperature are associated with grain coarsening induced by grain boundary migration during dynamic recovery process.