中文摘要：

采用半固态机械搅拌结合高速剪切工艺,以亚微米SiO2颗粒与熔体原位反应制备了不同MgAl2O4体积分数（0.5%、1%、2%、3%）的亚微米MgAl2O4（P）/Al-Mg-Si复合材料,分析了该复合材料的显微组织及相组成,并研究了MgAl2O4体积分数对该复合材料显微组织及拉伸性能的影响。结果表明：亚微米SiO2颗粒与基体合金原位反应生成粒径相似的亚微米MgAl2O4颗粒,基体则由α-Al、Mg2Si及Si相组成。MgAl2O4颗粒对α-Al晶粒具有细化作用。随MgAl2O4体积分数的增加,该复合材料的抗拉强度提高,伸长率降低,断裂方式由基体脆韧混合断裂转化为基体脆韧混合断裂与增强颗粒团聚脆断相结合。

英文摘要：

Using the in-situ reaction of sub-micron SiO2 particle and melt, the semi-solid mechanical stirring and high speed shearing process technics were applied to prepare sub-micron MgAl2O（P）/Al-Mg-Si composite with different MgAl2O4 volume fraction （0.5%,1%,2%,3 %）. The microstrueture and phase composition of the composite were analyzed, and, then, the effects of MgAl2O4 volume fraction on the microstructure and tensile property of the composite were studied. The results show that sub-micron SiO： particles completely react with matrix alloy, and the reaction product is MgAl2O4 particle with similar sizes, while the matrix is composed of α-Al, Mg2Si and Si phase. The MgAl2O4 particles have refinement effect on α-Al dendrites. With the increase of MgAl2O4 volume fraction, the tensile strength of the composite increases, while the elongation decreases. The fracture mode changes from brittle ductile mixed fracture of matrix to the combination of ductile mixed fracture of marix and brittle fracture of reinforcing particles agglomeration.