Sc对AlMg5Si2Mn合金组织与力学性能的影响

Effect of Sc on Microstructure and Mechanical Properties of AlMg5Si2Mn Alloy

研究了Sc含量对铸态AlMg5Si2Mn合金的显微组织,力学性能和断裂特征的影响。结果表明,添加适量的Sc对AlMg5Si2Mn合金中的初生α-Al和共晶Mg2Si具有显著的变质效果。随着Sc含量从0增加到0.25%,初生α-Al形貌由较大的块状转变为细小的球状,共晶Mg2Si的形貌由汉字状转变为纤维状或点状。Sc在合金中形成Al3Sc相,作为异质形核基底促进初生α-Al形核,并晶粒细化。Sc原子富集在共晶Mg2Si相的生长前沿形成成分过冷,Mg2Si相的生长被抑制。Sc的添加可以提高合金的抗拉强度和伸长率,与未变质合金相比,添加0.15%~0.25%Sc的合金拉伸性能最佳,抗拉强度和伸长率分别提高了20.9%和60.4%。

The effect of Sc content on microstructure,mechanical properties and fracture characteristics of as-cast AlMg5Si2 Mn alloy was studied.The results show that adding appropriate Sc have significant deterioration effects on primary α-Al and eutectic Mg2Si in AlMg5Si2Mn alloy.With the increase of Sc content from 0 to 0.25%,the morphology of primary α-Al changes from large block to small ball,and the morphology of eutectic Mg2Si changes from Chinese character to fiber or dot.Sc forms the Al3Sc phase in the alloy and as a heterogeneous nucleated substrate to promote primary α-Al nucleation and grain refinement.Sc atoms enrich in the growth front of eutectic Mg2Si phase form subcooling components,and the growth of Mg2Si phase is inhibited.The addition of Sc can improve the tensile strength and elongation of the alloy.Compared with the undeteriorated alloy,the alloy with 0.15%~0.25%Sc has the best tensile properties,and the tensile strength and elongation are improved by 20.9% and 60.4%,respectively.