SiC/Mg-5Gd-3Sm-0.5Zr复合材料的热压缩行为

Hot Compression Behavior of SiC/Mg-5Gd-3Sm-0.5Zr Composite

利用铸造法制备了SiC/Mg-5Gd-3Sm-0.5Zr复合材料。固溶处理后进行热压缩试验,应变速率为0.002~0.1 s^(-1),变形温度350~500℃,最大变形量70%。结果表明:所制备的SiC/Mg5Gd-3Sm-0.5Zr复合材料铸态组织由α-Mg基体、晶界处共晶组织以及SiC颗粒组成,经过固溶处理,晶界处共晶组织消失,复合材料组织由多边形的α-Mg晶粒和弥散分布的SiC颗粒组成。SiC/Mg-5Gd-3Sm-0.5Zr复合材料在热压缩过程中发生了动态再结晶,晶粒显著细化。由真应力-真应变曲线结合热压缩后组织分析,发现该复合材料适宜热加工的温度为450℃。经计算,SiC/Mg-5Gd-3Sm-0.5Zr复合材料应力指数为4.86,热变形激活能为280.525 kJ/mol。

SiCp/Mg-5Gd-3Sm-0.5Zr magnesium matrix composites were fabricated by casting method.After solution treatment,hot compression deformation was carried out at strain rate range of 0.002-0.1 s^(-1) and temperature of 350-500℃and maximum strain of 70%.The results showed that the microstructure of as-cast SiC/Mg5Gd-3Sm-0.5Zr composite consists ofα-Mg matrix,eutectic structure along grain boundary and SiC particles.After solution treatment,the eutectic structure along grain boundary disappears.The composite structure consists ofα-Mg with polygonal grains and dispersed SiC particles.Dynamic recrystallization(DRX)of SiCp/Mg-5Gd-3Sm-0.5Zr composite occurs during hot compression,and the grains are significantly refined.According to the true stress-true strain curves and the microstructure after hot compression,it is found that the suitable temperature for thermal processing of the composite is 450℃.After calculation,the stress exponent 4.86 and the hot deformation activation energy 280.525 kJ/mol are determined.