【摘要】 以Al-SiO₂为反应体系,借助半固态机械搅拌法,结合电磁搅拌分散工艺,制备5%α-Al₂O_3p/ZL109（体积分数）复合材料,并对重熔后的复合材料进行挤压铸造成型研究。结果表明:挤压铸造显著消除了复合材料因半固态机械搅拌卷气而引起的严重气孔缺陷,并细化基体α（Al）相晶粒;当压射比压达到80 MPa时,气孔缺陷完全消失,粗大的α（Al）树枝晶转变为细小的等轴晶,针状共晶Si细化成短棒状;分布在晶界的α-Al₂O₃颗粒也在一定程度上细化α（Al）晶粒。经80MPa挤压铸造的重熔复合材料的T6热处理态抗拉强度和布氏硬度分别达到347 MPa和136 HB,与ZL109基体相比,提高5.8%和5.4%;与未挤压复合材料相比,提高20.9%和18.3%。更多还原

【Abstract】 5% α-Al₂O₃/ZL109（volume fraction） composites were prepared by semi-solid mechanical stirring with aid of electromagnetic stirring through Al-SiO₂ system, and the remelted composites were also studied by squeeze casting. The microstructure observation results show that squeeze casting is very effectively to eliminate serious porosity defects caused by semi-solid mechanical stirring and refine the microstructure of ZL109 matrix. When the squeeze pressure reaches 80 MPa, the porosity defects completely disappear, coarse α（Al） dendrites transform into fine equiaxed crystals,and the eutectic Si is refined into rod-like. α-Al₂O₃ particles distributing along grain boundaries also refine α（Al） grains to some extent. The mechanical property test results show that the tensile strength and Brinell hardness of T6-treated composites remelted at 80 MPa are 347 MPa and 136 HB, respectively, which increase by 5.8% and 5.4% compared with those of remelted ZL109 matrix alloy, and increase by 20.9% and 18.3% compared with those of non-squeeze casting composites.更多还原