搅拌铸造颗粒增强铝基复合材料颗粒分散性研究

Research on the Dispersion of SiC Particles During the Fabrication of SiC_p /Al Composites by Stir Casting

采用半固态搅拌铸造法制备了SiC颗粒增强铝基复合材料,定位置、分阶段提取制备过程中的浆料试样,使用光学显微镜和扫描电子显微镜观察试样的微观结构,并用阿基米德法测量试样密度。结果表明,SiC颗粒在熔体中的存在形式分3种:粉末状聚集团、聚集的小团体和分散的单个颗粒。其中,聚集成团的粉末与合金熔体完全没有润湿,聚集的小团体与合金熔体部分润湿。SiC颗粒完全润湿之后才能完全的分散,同时气体逐渐从熔体中排出。最终,确立了搅拌铸造法制备颗粒增强铝基复合材料中增强颗粒分散规律的经验模型。

SiC particulate-reinforced Al matrix composite was synthesized by semi-solid stir casting technique in the present investigation.Specimens were obtained in the same position by stages in the preparation process of composite semi-solid slurry.Microstructure of these samples was investigated with optical microscope and SEM（scanning electron microscope）.Each sample＇s density was measured according to Archimedes law.Experimental results show that there were mainly three forms of SiC particles in the metal melt： powdered SiC particles,agglomerated SiC particles and dispersed SiC particles.There is no wetting for the powdered SiC particles,poor wetting for agglomerated SiC particles and good wetting for dispersed SiC particles with the alloy melt.Only after attaining good wetting,can the SiC particles be well-dispersed,and can gas remove from semi-solid slurry gradually.A kind of empirical dispersion model of ceramic particle in alloy melt during semi-solid stir casting was presented finally.