Ca和Mn添加对铸态及热处理态Al-Mg-Si合金的微观组织、力学性能和导电性能影响

Influence of Ca and Mn on Microstructure,Mechanical Properties,and Electrical Conductivity of As-Cast and Heat-Treated Al-Mg-Si Alloys

制备了Al-0.59Mg-0.54Si-X(X=0,0.253Ca,0.253Mn)合金来探究微量Ca、Mn添加对铸态、固溶态及时效态Al-0.59Mg-0.54Si-X合金的微观组织、力学性能及导电性能的影响。研究发现,Ca和Mn添加都显著细化了α-Al的晶粒尺寸。Ca能够诱导高密度的Mg_(2)Si和Al_(2)Ca颗粒在铸态α-Al晶粒中析出,使合金在铸态下具有最优的力学性能。固溶和时效处理会导致颗粒粗化并且偏聚在晶界,使合金的力学性能急剧下降,但其电导率却增加到了52.44%IACS。Mn添加使得晶界上的粗大β-Al_(5)FeSi杂质相转化成α-Al(FeMn)Si颗粒,并且诱导Mg_(2)Si和AlMn颗粒在铸态合金中析出。因此经过固溶和时效处理后的Al-0.59Mg-0.54Si-0.253Mn合金表现出最优的力学性能以及可接受的电导率。

The Al-0.59Mg-0.54Si-X(X=0,0.253Ca,0.253Mn)alloys were prepared to investigate the effect of minor addition of Ca and Mn on the microstructure,mechanical properties,and electrical conductivity of the Al-0.59Mg-0.54Si-X alloys after casting,solidsolution,and aging treatments.Results show that the Ca and Mn addition can significantly refine the grains ofα-Al matrix.Moreover,Ca can induce the precipitation of Mg_(2)Si and Al_(2)Ca particles with high contents in the as-castα-Al grains,which contributes to the optimum mechanical properties of alloys.The solid-solution and aging treatments cause the coarsening of particles and the particle segregation at the grain boundaries,leading to the rapid decline in mechanical properties but an extraordinary increase in electrical conductivity(52.44%IACS)for the alloys.Mn addition can transform the coarseβ-Al_(5)FeSi impurity phase at the grain boundaries into theα-Al(FeMn)Si particles and also induce the precipitation of Mg_(2)Si and AlMn particles in the as-cast alloys.Consequently,the Al-0.59Mg-0.54Si-0.253Mn alloy after solid-solution and aging treatment exhibits the optimal mechanical properties and acceptable electrical conductivity.