脉冲电流对Al-12Si半固态压铸板组织及性能影响

Effects of Pulse Current on Microstructure and Properties of Al-12Si Semisolid Die-casting Plate

将12 V脉冲电流引入Al-12Si合金半固态浆料制备过程中,并压铸成形表面品质良好的3组板坯。对比研究发现,控制温度为570℃下,脉冲电流可有效细化α-Al枝晶并使其分布更均匀。共晶相中Si含量下降,共晶相得到细化;在脉冲电流与变质剂的共同处理下,α-Al枝晶最为细小,其共晶相中Si含量最低,呈细小短棒状及颗粒状。另外,电脉冲结合Sr变质处理下板坯的抗拉强度为226.5 MPa,较传统产品提高了约13%。断口呈现以微孔聚集为主、沿晶断裂为辅的韧性断裂机制。

Pulse current of 12 V was induced into preparing process of Al-12Si semisolid slurry to fabricate three groups of plates.The results indicate thatα-Al dendrites are effectively refined with uniform distribution by pulse current at 570℃,where the Si content in eutectic phase is decreased and eutectic phase is refined.Under the synergy of pulse current and Sr modifier,α-Al dendrites are refined to minimum value,presenting small short rods and particles shapes with the lowest Si content.Moreover,the tensile strength of die-casting plates modified by pulse current combined with modifier Sr reaches 226.5 MPa,which is 13%higher than that of traditional ones.The fracture is dominated by micropore aggregation,supplemented by intergranular fracture.