热处理对镁合金第二相析出及性能的影响

Effects of heat treatment on secondary phase precipitation and properties of magnesium alloy

AZ系列镁合金是最常用的镁合金。Al和Zn通过固溶强化和第二相析出提高其机械性能,其中Mg17Al12第二相的形貌和数量起着重要的作用。在这项研究中,轧制的AZ31、AZ61和AZ91板材经过300℃,5 h退火,液氮低温处理6 h和160℃,18 h时效处理。发现仅通过退火和深冷处理,第二相的析出较少,不同的深冷处理时间对塑性没有明显影响。通过时效处理,析出在晶粒内的第二相增加,塑性也显著提高,同时强度也增加。

AZ series magnesium alloys are the most commonly used magnesium alloys.The alloying additions Al and Zn improve mechanical properties both by solid solution strengthening and secondary phase precipitation,and the morphology and quantity of the second phase of Mg17Al12 play an important role.In this research,the rolled sheets of AZ31,AZ61,and AZ91 were treated by annealing at 300℃for 5 h,cryogenic treatment with liquid nitrogen for 6 h,and aging at 160℃for 18 h.It was found that few second phase precipitated in the annealing and cryogenic treatments,and the cryogenic treatment time has no obvious effect on plasticity.During the aging treatment,more second phase precipitated in the grains and caused a significant increase in plasticity and an increase in strength.