【摘要】 利用扫描电镜及高分辨透射电镜对复合添加Cr、Bi元素的ZA84镁合金的时效硬化及微观组织进行了研究。结果表明:在ZA84合金中复合添加微量的Cr、Bi元素能显著增强合金时效硬化效果。ZA84-0.2Cr-0.5Bi合金经160℃时效,在时效初期基体存在严重的晶格畸变并含有数量较多的晶体缺陷。峰时效阶段合金微观组织中析出大量呈棒状或块状的MgZn₂相以及粒状的Bi₂Mg₃相,此时合计峰时效硬度HV达到924.8 MPa。随着时效时间的延长,沉淀相继续长大并粗化,其硬度也略有下降。更多还原

【Abstract】 The age hardening and microstructure of ZA84 magnesium alloy with the combined addition of Cr and Bi was studied by SEM and HRTEM. The results show that a trace amount of Cr and Bi has a significant enhancement effect on the hardness of aging. When the ZA84-0.2Cr-0.5Bi alloy was aged at 160 °C, during the early aging period, the matrix has serious lattice distortion and a large number of crystal defects. The microstructure at the peak aging consists of a large number of rod-like or blocky β₁-MgZn₂ phases and granular Bi₂Mg₃ phases, and the peak hardness HV value is 924.8 MPa. When ageing proceed, the precipitates coarsening results in the hardness value reduction.更多还原