【摘要】 利用金属型铸造制备了原位自生Mg2Si/Mg-Al基复合材料,研究了热处理对该材料组织与性能的影响。结果表明T4处理改变了Mg2Si/Mg-Al基复合材料中Mg2Si的形貌与分布。随着保温时间的延长,棱状枝晶Mg2Si相发生熔断、球化,最终成为尺寸为10-30μm的颗粒;同时β-Mg17Al12相溶入到α-Mg基体中,在随后的时效过程中发生沉淀析出。由于β-Mg17Al12相的溶解,T4处理会降低该材料的硬度,但随后的时效析出可提高其硬度,415℃×12h固溶处理后175℃×16h(T6)时效,硬度可提高14.9%。热处理过程中棱状枝晶Mg2Si相的粒化可用吉布斯-汤姆逊定理解释。更多还原

【Abstract】 In-situ Mg₂Si/Mg-Al matrix composite was prepared by permanent mold casting.The effects of heat treatment on microstructure and properties of in-situ Mg₂Si/Mg-Al matrix composite were investigated.The results show that the morphology and distribution of Mg₂Si in the Mg₂Si/Mg-Al matrix composite are changed during T4 heat treatment.With increasing holding time,the roughly prismatic dendritic Mg₂Si phase tends to be dissolved and broken and spheroidized and finally transformed into particles with size of 10-30μm; at the same time,the β-Mg 17 Al 12 phase is dissolved into the matrix to form supersaturated solid solution of α-Mg,then precipitates during subsequent ageing heat treatment.Due to solution of β-Mg 17 Al 12 phase,the hardness of the composite decreases after T4 treatment,and then increases during subsequent ageing treatment.The hardness is improved by 14.9% after 415℃×12h solution heat treatment and then aging at 175℃ for 16h（T6 treatment）.The spheroidization of roughly prismatic dendritic Mg₂Si phase during heat treatment can be explained by Gibbs-Thomson’s theorem.更多还原