中文摘要：

采用金相显微镜、XRD、SEM、极化曲线以及盐雾腐蚀实验等方法对压铸、固溶（T4）及人工时效（T6）AZ91D镁合金样品的组织结构演变及腐蚀行为进行了研究。结果表明,薄壁压铸AZ91D镁合金在415℃下保温6h后,β-Mg17Al12相完全溶解;200℃人工时效2h后β相首先在晶界处析出,且随着时效时间的延长,析出相逐渐增多;T4样品由于β相的溶解导致其耐腐蚀性最好,仅在局部形成微小的腐蚀点,T6样品由于微电池腐蚀效应导致其耐腐蚀性最差,而且随时效时间延长,耐腐蚀性逐渐降低。

英文摘要：

The microstructure and corrosion properties of AZ91D Mg alloy were investigated using metallurgical microscope, XRD, SEM, polarization curves and salt spray testing. The sam ples were adjusted by T4 and T6 treatment. The results show that β-Mg17AI12 phase entirely dis solved under 415 ℃ for 6 h. The β phase precipitated first on the grain bounderies under 200 C for 2 h. With increasing aging time, the precipitation phase increased. Because of the dissolution of β phase, the T4 sample showed a best corrosion resistance compared with the die-casting alloy and the T6 sample. The micro-pitting only appeared on the surface. The corrosion resistances of the T6 samples were worst owing to mierogalvanic corrosion and the corrosion resistance of the aged samples reduced with increasing aging time.