目的 提高AZ91D镁合金的耐腐蚀性能。方法 通过电沉积方法在氯化胆碱-尿素离子液体中于镁合金表面电沉积Ni-Mn合金膜层。经过均一化前处理，在镁合金表面电沉积铜层，以提高后续Ni-Mn合金膜层与基体的结合力。利用扫描电镜（SEM）、能谱仪（EDS）、X射线衍射仪（XRD）研究了Mn元素对膜层微观形貌、成分和相结构的影响，并通过电化学方法评价了镀层的电化学腐蚀行为。结果 引入Mn元素后，膜层表面微观形貌从锥状演变为肿瘤状，且Ni-Mn合金膜层的Mn含量取决于电流密度，其含量随着电流密度的增加而增加。与纯Ni膜相比，引入少量Mn元素可以提高其耐腐蚀性能，然而引入过多的Mn元素，膜层的耐腐蚀性能将弱于纯Ni膜。结论 当电沉积Ni-Mn膜层含有3.078%（原子数分数）Mn时，具有最佳的耐腐蚀性能，其自腐蚀电流密度Jcorr=0.301 μA/cm2，自腐蚀电位Ecorr=?0.157 V（vs. SCE）。

The work aims to improve corrosion resistance of AZ91D magnesium alloy. Ni-Mn alloy film was electrodeposited on the surface of magnesium alloy in the choline chloride-urea ionic liquid by electrodeposition method. After homogenization pretreatment, the copper layer was electrodeposited on the surface of magnesium alloy to improve the adhesion between subsequent Ni-Mn alloy film and the substrate. The effects of Mn element on the surface morphology, chemical composition and phase structure of the film were studied by using scanning electronic microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction spectroscopy (XRD). Once Mn was incorporated into the film, the surface morphology transformed from pyramid-like to tumor-like clusters. Moreover, Mn content of Ni-Mn alloy film rest on current density and increased as the current density increased. Corrosion resistance of the coating could be improved by introducing a little Mn compared with pure Ni film. However, the corrosion resistance of the film was weaker than that of the pure Ni film when too much Mn was introduced. The Ni-Mn alloy film, when containing 3.078at.% Mn, shows the best corrosion resistance with self-corrosion current Jcorr of 0.301 μA/cm2 and corrosion potential Ecorr of ?0.157 V (vs. SCE).