Al_2O_3-SiO_2/AZ91D镁基复合材料的挤压浸渗制备工艺及微观组织和界面的研究

采用挤压浸渗法制备Al_2Or_3-SiO_2/AZ91D复合材料.改进制备工艺,利用价格低廉且来源广泛的硅酸铝短纤维作增强体,用磷酸铝作黏结剂制得预制体.在预制体温度660℃、模具温度560℃、浇注温度760℃和压力30～50MPa下,通过挤压浸渗工艺制备AZ91D镁基复合材料.采用光学显微分析、XRD衍射分析、SEM扫描分析等方法研究该复合材料.结果表明,镁与磷酸铝黏结剂反应后在界面上生成一定数量的Mgo颗粒和少量的MgAl_2O_4颗粒,致使硅酸铝增强纤维和镁合金基体之间形成较强界面结合.复合材料组织致密、无明显孔洞及夹杂等铸造缺陷.其界面上的反应产物主要有MgO、MgP_4、MgAl_2O_4和Mg_2Si

Microstructure, Interface and Fabricating Process of Al_2O_3-SiO_2/AZ91D Composites Prepared by Squeeze Infiltration

Al_2O_3-SiO_2/AZ91D composites were fabricated by squeeze infiltration process. Taking low price and extensive source silicate aluminum short fiber as reinforcement, and phosphate aluminum as binder, the fabricating process was improved. Al_2O_3-SiO_2/AZ91D composites was prepared by the optimum technique of squeeze casting, that was, preform-body temperature 660 ℃, mould temperature 560 ℃, pouring temperature 760 ℃ and pressure 30～ 50 MPa. The reaction products were investigated by optical microscopic, XRD and SEM. The results show that an ideal stronger interface is formed by the chemical reaction between magnesium alloy matrix and phosphate aluminum binder due to the production of MgO particles and a little MgAl_2O_4 particles in the inferface. The structure of the composites is uniform without casting defects such as shrinkages and inclusions, and there are MgO, MgP_4, MgAl_2O_4, Mg_2Si, and so on as the main reaction products on its interface.