通过在铸造过程中对熔体进行二元和三元变质处理,制备了硅质量分数为18%的A390过共晶铝硅合金:通过金相分析、扫描电镜观察、拉伸性能测试、耐磨性能测试等手段研究了变质处理对A390过共晶铝硅合金组织和性能的影响.结果表明:A390合金经过变质处理后,初晶硅棱角得到钝化,尺寸小于30 μm,共晶硅出现球化,晶粒尺寸减小:变质后合金力学性能明显提高,其中经三元变质处理后其室温抗拉强度与伸长率较未变质处理的分别提高了31%与150%:耐磨性能也有一定程度的改善,三元变质处理后的磨损机理以微观切削为主.

The A390 hypereutectic Al-Si alloy with 18wt% Si content was prepared through the melt modified by binary and ternary modifiers during the casting process.The influence of modification on microstructure and mechanical properties of A390 hypereutectic Al-Si alloy was investigated by optical microscopy analysis,scanning electron microscopy observation,wear resistance test and tensile strength test.The results show that after the modification of A390 alloy,the corner angle of the primary Si was inactivated,and its size was below 30 μm.Eutectic Si was spheroidized,and the grain was refined.Mechanical properties of the modified alloy were improved apparently.After ternary modification,compared to non-modification,the elongation and tensile strength of A390 alloy at room temperature had been increased by 150% and 31%,respectively.Wear resistance of the A390 alloy was also improved.The wear resistance in ternary modification was mainly microscopic cutting.