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采用纯Bi对原位自生Mg2Si/Al复合材料进行变质;采用金相显微镜等观察了变质前后材料的微观组织;测试了材料的拉伸性能;并对变质前后合金的断口形貌进行了分析。结果表明,在原位自生Mg2Si/Al复合材料中添加适量的金属Bi对初生Mg2Si和共晶Mg2Si能够同时起到良好的变质作用,初生Mg2Si的形貌由粗大的树枝状或多角形块状转变为细小的块状,尺寸由70μm减小到6μm,而共晶Mg2Si则由粗大的片状转变为细小的片状、纤维状或点状。经1.0%的Bi变质后,材料的拉伸性能得到大幅度提高,抗拉强度从175MPa提高到260MPa,提高了48.6%,伸长率从3.5%提高到7.0%。
The pure Bi was used to degenerate the in-situ Mg2Si / Al composites. The microstructure of the as-prepared Mg2Si / Al composites was observed by metallographic microscope. The tensile properties of the composites were tested. The fracture morphology of the alloy before and after modification was analyzed. The results show that adding proper amount of metal Bi into the in-situ Mg2Si / Al composites can play good metamorphism simultaneously with the primary Mg2Si and eutectic Mg2Si. The morphology of the primary Mg2Si is changed from coarse dendritic or polygonal block As a small lumps, the size decreased from 70μm to 6μm, and eutectic Mg2Si from coarse sheet into small flake, fibrous or punctate. After 1.0% Bi was modified, the tensile properties of the material were greatly improved. The tensile strength increased from 175MPa to 260MPa, increased by 48.6% and the elongation increased from 3.5% to 7.0%.