轧制对Al-6Zn-2Mg-2Cu合金时效组织及MgZn_2相析出动力学的影响

Effect of rolling on aging microstructure of Al-6Zn-2Mg-2Cu alloy and precipitation kinetics of MgZn_2 phase

利用光学显微镜及X射线衍射仪对轧制后时效的Al-6Zn-2Mg-2Cu铝合金的显微组织及MgZn_2相的体积分数进行表征,研究了轧制变形量对Al-6Zn-2Mg-2Cu铝合金时效处理后的组织及MgZn_2相析出动力学的影响,结果表明:轧制变形后该合金显微组织沿轧制方向呈流线型分布,且随轧制变形量的增大,时效态组织出现再结晶现象;时效过程中MgZn_2相优先在晶界处析出;随着轧制变形量的增大,MgZn_2相的析出速度增大;结合试验数据,由JMAK方程计算两种轧制变形量的Al-6Zn-2Mg-2Cu铝合金在同一时效处理温度下,经过不同的时效时间,MgZn_2析出相的体积分数的拟合曲线分别为y=1-exp(-0.00060t^(0.5306))和y=1-exp(-0.00063t^(0.5276))。

By optical microscopy and X-ray diffraction analysis, the microstructure and the volume fraction of the MgZn2 phase of the rolled and aged Al-6Zn-2Mg-2Cu aluminum alloy were characterized and the influence of rolling deformation on the microstructure and dynamics of MgZn2 phase of Al-6Zn-2Mg-2Cu aluminum alloy after aging treatment was studied. The results show that after rolling deformation, the microstructure of the alloy is streamline distribution along the rolling direction, and with the increase of the rolling deformation, the microstructure of the aged state appears recrystallization phenomenon. The MgZn2 phase precipitates preferentially at the grain boundaries during the aging process. The precipitation rate of MgZn2 phase increases with the increase of rolling deformation. In accordance with experimental data, the volume fraction of MgZn2 precipitates in Al-6Zn-2Mg-2Cu aluminum alloy with two rolling deformation magnitude under the same aging temperature and different aging time is calculated by the JMAK equation. The fitting curves are y = 1 -exp（ -0.00060t^0.5306） and y = 1 - exp （ -0. 00063 t^0. 5276 ） , respectively.