固溶处理对7475铝合金组织和拉伸性能的影响

Effect of solution treatment on microstructure and mechanical properties of 7475 Al alloy

利用透射电子显微镜(TEM)和万能材料试验机,研究了单级固溶和双级固溶对7475铝合金微观组织和拉伸性能的影响.结果表明,7475铝合金最佳的固溶制度为470℃/40 min+500℃/25 min双级固溶.在此制度下固溶处理,随后进行120℃/5 h+163℃/18 h双级时效,σ_(b)、σ_(0.2)和δ分别为499 MPa、454 MPa和12.9%.与单级固溶相比,双级固溶后固溶度显著提高,时效时析出驱动力增加,析出相的临界形核尺寸减小,形核率增加.故时效处理后,基体析出相数量更多,且更细小弥散,达到时效强化效果.

The effects of single-stage solution and double-stage solution on microstructure and tensile properties of 7475 Al alloy have been investigated by transmission electron microscopy(TEM)and universal material testing machine.The results show that the optimal parameter of solution treatment for 7475 Al alloy is double-stage solution at 470℃/40 min+500℃/25 min.After double-stage aging of 120℃/5 h+163℃/18 h,σ_(b,)σ_(0.2) andδare 499 MPa,454 MPa and 12.9%,respectively.Compared with single-stage solution,the solid solubility of double-stage solution is significantly improved,the precipitation driving force increases,the critical nucleation size of the precipitated phase decreases,and the nucleation rate increases.After aging treatment,the number of matrix precipitates is more,and finer.Thus aging strengthening has been achieved.