用盐雾试验、扫描电镜能谱仪、X射线衍射仪等,对加入不同Ce含量的含铈AZ91D镁合金的显微组织和盐雾腐蚀性能进行了分析.结果表明:当加入0.69%Ce时,可使合金铸态组织明显细化,且网状β相呈粒状弥散分布于晶界上,同时有大量针状物Al4Ce相出现；而加入0.93% Ce时,合金铸态组织有粗化趋势,且针状物长大成杆状.12 h腐蚀试验结果表明,加入0.26% Ce和0.93% Ce的合金,腐蚀速率先迅速增加而后又明显降低；而加入0.69% Ce的合金,腐蚀速率保持恒定.随着NaCl溶液浓度的增加,AZ91D合金的腐蚀速率增长较快；加入0.26% Ce后,合金腐蚀速率增长缓慢；加入0.69% Ce后,合金的腐蚀速率随浓度增加逐渐降低；加入0.93% Ce的合金在低浓度下的腐蚀速率略有升高,而在高浓度下的腐蚀速率迅速降低.合金的腐蚀形貌均表现为不均匀腐蚀,腐蚀产物主要由Mg(OH)2组成.含稀土合金的腐蚀产物中还有Al4Ce.稀土Ce提高AZ91D镁合金腐蚀性能的原因归结为Ce对组织的细化作用以及对Al元素偏析程度的降低.

The microstructure and corrosion properties of AZ91D magnesium alloys with the addition of Ce were observed and analyzed.The results indicated that the casting microstructure was refined obviously and reticular β-phase that exhibited graininess dispersion was distributed at grain boundaries,and a large amount of spicule Al4Ce phase appeared when the addition of Ce was 0.69%.But when the addition of Ce was 0.93%,the casting microstructure of the alloy was more coarse and spicule compound grow up to be rhabditiform.The corrosion rate of the alloy with the 0.26% Ce and 0.93% Ce increased rapidly in the beginning and then reduced obviously;but the corrosion rate of the alloy with 0.69% Ce kept constant.The corrosion rate of AZ91D magnesium alloy increased with the increase of NaCl concentration;The corrosion rate of the alloy with 0.26% Ce increased slowly;The corrosion rate of the alloy with 0.69% Ce decreased with the increase of NaCl concentration;The corrosion rate of the alloy with 0.93% Ce increased a little in low concentration,but decreased quickly in high NaCl concentration.The corrosion feature showed non-uniform corrosion.The corrosion product mainly consisted of Mg(OH)2.There was Al4Ce compound observed in the corrosion products of AZ91D magnesium alloys with Ce.The improvement of corrosion resistance of the alloy with Ce resulted from the refinment of microstructure and reduction of segregation of Al element.