锶及固溶处理对AM50镁合金组织和高温力学性能的影响

研究了添加不同含量的锶(Sr)及固溶处理(T4)对AM50镁合金显微组织和高温(150℃)拉伸性能的影响。结果表明:当Sr加入量为0.7wt%和1.4wt%时,AM50合金中形成了层片状的Al4Sr新相,而Mg17Al12相被抑制形成,固溶处理使Al4Sr相由层片状转变为颗粒状。当Sr加入量为2.8wt%和3.5wt%时,AM50合金中形成了骨骼状的Sr5Al9新相,固溶处理使热稳定性较高的Sr5Al9相由骨骼状向层片状和颗粒状转变。加入Sr能细化晶粒并显著提高合金在150℃下的拉伸性能,固溶处理明显提高了AM50-2.8Sr和AM50-3.5Sr合金高温下的抗拉强度,但对AM50-0.7Sr和AM50-1.4Sr合金高温拉伸性能影响较小。

Effects of Sr addition and solid-solution treatment on microstructure and elevated temperature mechanical properties of AM50 magnesium alloy

Effects of Sr addition and solid-solution treatment(T4)on microstructure and tensile properties at 150 ℃ of AM50 magnesium alloy were studied.The results indicate that lamellar Al4Sr phase forms and Mg17 Al12 phase is not observed for AM50 alloys with the addition of 0.7 wt% and 1.4 wt% Sr.After solid-solution treatment,the lamellar Al4Sr phase is transformed to granular one.When 2.8 wt% and 3.5 wt% Sr are added to the AM50 alloy,skeleton-like phase Sr5Al9 forms.After solid-solution treatment,the Sr5Al,phase is changed to be lamellar and granular.The grain size of Sr modified AM50 alloy is much finer than that of base alloy,and tensile properties at 150℃ of the cast AM50 alloy containing Sr are obviously improved.After solid-solution treatment,ultimate tensile strength of AM50-2.8Sr and AM50-3.5Sr alloys at 150℃ are enhanced noticeably,however,no significant improvement of elevated temperature mechanical properties for AM50-0.7Sr and AM50-1.4Sr alloys is observed.