中文摘要：

通过光学显微镜、扫描电镜、透射电镜、电子背散射衍射以及硬度测试研究轧制变形速率对7050铝合金微观组织演变的影响,分析轧制变形速率影响合金淬火敏感性的微观机理。结果表明：变形速率较小时（5 s？1和8 s？1）,合金再结晶分数低,试样中存在大量的亚组织结构,亚晶粒的尺寸较小,晶界较难分辨,为小角度晶界,固溶慢速淬火的试样中少量η平衡相在亚晶界上形核析出;随着变形速率的增加,亚晶长大,晶界平直逐渐向大角度晶界转变,η平衡相在晶界上析出增加,在亚晶内部亦有明显析出;当变形速率升高至15 s？1时,固溶后试样的再结晶百分数明显增加,在大角度晶界处以及再结晶晶粒内出现大量非均匀形核析出,同时,在亚晶区域观察到较多析出,与微观组织演变对应,合金时效态硬度性能测试结果表明：随着轧制变形速率增加,慢速淬火的试样力学性能损失变大,合金淬火敏感性增加。

英文摘要：

The optical microscopy,scanning electron microscopy,transmission electron microscopy,electron backscatter diffraction,hardness and electric conductivity measurements are employed to study the effect of deformation rate on the microstructure evolution and quench sensitivity of 7050 aluminum alloy.The results show that,the recrystallized fraction is very low with deformation rate at low level of 5 s-1 and 8 s-1.There are a large number of sub-structures in the samples and the average size of the sub-grains is quite small.The sub-grain boundary is hard to distinguish,which is called small-angle grain boundary,and a few equilibrium η phases mainly precipitates at these boundaries during air quenching after solution.With increasing the deformation rate,the sub-grains coarsen and the gradual boundary misorientation occurs,and more equilibrium η phase precipitates at the sub-grain boundary.Rolling at high deformation rate（15 s-1） can increase the recrystallized fraction seriously.The equilibrium phases precipitate at the high angle grain boundaries and inside the recrysatllized grains with high density.Meanwhile,some precipitates are also observed inside the sub-grains.Actually,the incoherent Al3Zr particles play a vital role in the precipitation of equilibrium η phase during air quench.The results of hardness and electric conductivity tests indicate that,with increasing the rolling rate,the loss of mechanical properties subject to the slow quenched samples increases,and the quench sensitivity of the alloy increases.