SiC_p/AZ91D复合材料真空压力浸渗制备工艺及微观组织的研究

Microstructures and Fabricating Process of SiC_p /AZ91D Composites by Vacuum Pressure Infiltration

采用真空压力浸渗装置制备SiCp/AZ91D复合材料。对制备工艺进行了改进,提出了以SiC颗粒覆盖法保护镁合金熔体的措施,可以有效解决熔剂覆盖法易造成的熔剂夹杂问题;在压力0.4MPa、浸渗温度700℃、保压5min的条件下,制备SiC单一颗粒尺寸为5μm、体积分数为44.7%的SiCp/Mg复合材料;并且成功制备32μmSiC单一颗粒体积分数为56.4%的SiCp/AZ91D复合材料。经过光镜、扫描电镜和X射线衍射仪分析表明,采用SiC颗粒覆盖法制备SiCp/AZ91D复合材料组织致密、无明显孔洞及夹杂等铸造缺陷,有新相Mg2Si生成。

SiCp/AZ91D composites were fabricated by vacuum pressure infiltration process, in which the SiC particles coverage method was used to protect magnesium alloy melt, and through the method, the flux inclusions easily occurred in the flux coverage process could be removed. The preform with single SiC particle size of 5 μm and volume fraction of 44.7% and even with size of 32 μm and volume fraction of 56.4% was successfully infiltrated under the pressure of 0.4 MPa, holding time of 5 min and infiltration temperature of 700 ℃. The analysis results by means of OM, SEM and XRD indicated that SiC particles are uniformly distributed in the magnesium matrix without casting defects such as shrinkage and inclusion, and the Mg2Si phase is generated in the SiCp/AZ91D composites.