时效析出对Al-Zn-Mg-Cu合金热稳定性的影响

Effect of Aging Precipitation on Thermal Stability of Al-Zn-Mg-Cu Alloy

采用透射电镜、常温力学性能测试等手段,研究了合金成分与回归再时效工艺对Al-Zn-Mg-Cu合金热暴露过程中力学性能和微观组织的影响。研究结果表明,GP区和η'相的粗化是导致铝合金热暴露过程中强度降低的主要原因。在120℃热暴露时,高度弥散分布的GP区有利于提高Al-Zn-Mg-Cu合金的热稳定性,而在150℃热暴露时,添加与空位有较高结合能的Zr和Ti元素可以降低溶质原子的扩散速度和析出相的粗化速度,抑制GP区向η'相的转变。

Effects of chemical compositions and technology of retrogression re-aging on microstructures and mechanical properties during thermal exposure were studied by transmission electron microscope analysis and mechanical properties test at room temperature. Results showed that the coarsening of GP and η' was responsible for the strength degradation of the investigated aluminum alloy during thermal exposure. When the alloy was exposed at 120 ℃, GP with highly dispersive distribution enhanced thermal stability of the alloy. When exposed at 150 ℃, the high Zr-vacancy and Ti-vacancy binding energy in alloy inhibited the diffusion of solute atoms and the coarsening of precipitates, thus, delayed the transition from GP to η' in the matrix.