镧-铈混合添加对A356铝合金的变质研究

Modification of A356 Aluminum Alloy by Lanthanum-Cerium Mixed Addition

采用金相显微镜、钨灯丝扫描电镜、场发射扫描电镜等手段,研究了0~0.35%的La、Ce混合稀土添加对A356铝合金的微观组织和力学性能的影响。结果表明,当混合稀土添加量为0.35%时,A356铝合金的组织与力学性能最好,α-Al晶粒等效直径和二次枝晶臂间距(SDAS)均达到最小值,分别为24.24μm和38.07μm,共晶Si细化理想,抗拉强度和屈服强度分别达到178.5 MPa、145.6MPa,断裂类型由脆性断裂逐渐变为韧性断裂。

The effects of mixed additions of La and Ce in the range of 0~0.35%on the microstructure and mechanical properties of A356 aluminum alloy were investigated by metallographic microscope,tungsten filament scanning elec⁃tron microscope and field emission scanning electron microscope.The results reveal that optimal microstructure and mechanical properties of A356 aluminum alloy are obtained with mixed rare earth addition of 0.35%,and the equiva⁃lent diameter and SDAS value ofα-Al grains reach the minimum value of 24.24µm and 38.07µm,respectively,with the satisfied eutectic silicon refinement.The tensile strength and yield strength reach the maximum values of 178.5 MPa and 145.6 MPa,and the fracture type is gradually changed from brittle fracture to ductile fracture.