粉末冶金制备50%SiC_p/Al复合材料的结构及性能

Microstructures and properties of 50%SiC_p/Al composites fabricated by powder metallurgy

采用球磨加常压烧结的粉末冶金工艺制备50%SiC_p/6061Al(体积分数)复合材料,研究了烧结温度对该高体积分数SiC_p/Al复合材料结构与性能的影响。结果表明:球磨有利于形成成分均匀的50%SiC_p6061Al复合粉体;随着烧结温度的升高,50%SiC_p/6061Al复合材料的致密度及抗弯强度先增后减。710℃烧结的复合材料性能最佳,致密度达到97%,抗弯强度大于400 MPa。该复合材料中SiC_p呈解理断裂,而Al合金基体呈韧性撕裂的断裂特征。750℃烧结的50%SiC_p/6061Al复合材料中,SiC_p/Al界面反应加剧,生成较多的Al4C3相,导致复合材料结构劣化,性能降低。

50%SiC_p/6061 Al（volume fraction） composites were fabricated using powder metallurgy technique via ball-milling and pressureless sintering. The effect of sintering temperature on microstructures and properties of the SiC_p/Al composites with high SiC_p volume fraction was especially stressed. The results show that ball milling is beneficial to the uniform composition distribution of the 50%SiC_p/6061 Al composites powder. With increasing the sintering temperature, the density and bending strength of the 50%SiC_p/Al composites increase initially and then decrease. The SiC_p/Al composite sintered at 710 ℃ has the optimal properties, i.e. the relative density is 97% and the bending strength is above 400 MPa. The Si C particles and Al alloy matrix in the composite follow the cleavage and plastic tearing fracture modes, respectively. As the sintering temperature increases to 750 ℃, an intensive SiC_p/Al interfacial reaction takes place to form more Al4 C3 phase, resulting in the structural degradation and property reduction of the SiC_p/Al composite.