7055铝合金非等温时效析出过程及力学性能变化

Precipitation Process and Mechanical Properties of 7055 Aluminum Alloy During Non-Isothermal Aging

文章将一种非等温时效工艺应用于7055铝合金中,使合金力学性能相比T6时效有所提升的同时极大地缩短了时效时间。研究表明,在时效前期的快速升温阶段(100℃~175℃)中,析出相高速形核。降温阶段前期(175℃~145℃),析出相在高温环境下迅速长大;降温阶段后期(125℃~100℃)的低温环境又抑制了析出相的粗化并为新相的析出提供了稳定的环境从而导致了二次析出现象的出现。对比T6时效,非等温时效后的合金内部析出相体积分数上升了0.7%,析出相平均尺寸增大了0.98nm。非等温时效后的合金屈服强度到达660MPa,延伸率为11.5%,抗拉强度723MPa;而时效总用时仅5.625h,相比T6时效缩短了76.6%的时间。

In this paper,a non-isothermal aging(NIA)process is applied to 7055 aluminum alloy,which improved the mechanical properties of the alloy compared with T6 aging and greatly shortened the aging time.The results show that the precipitates nucleate at high speed during the rapid heating stage(100℃~175℃)in the early aging stage.In the early cooling stage(175℃~145℃),the precipitated phase grows rapidly under high temperature environment.In the late cooling stage(125℃~100℃),the low tempearture environment inhibited the coarsening of precipitated phase and provided a stable environment for the precipitation of new phase,leading to the emergence of secondary precipitation phenomenon.Compared with T6,the volume fraction of precipitated phase in the alloy after non-isothermal aging increases by 0.7%,and the average size of precipitated phase increases by 0.98nm.the yield strength,elongation and tensile strength of the alloy afer non-isothermal aging reach 660MPa,11.5%,723MPa respectively.The total aging time is only 5.625h,which is 76.6%shorter than T6.