目的 提高AZ91HP镁合金的耐蚀及耐磨性，扩大其应用范围。方法 采用H3PO4+Na3PO4酸洗液+NH4HF2活化的无铬前处理工艺，再直接化学镀，获得镍磷合金镀层，随后对镀层进行了热处理。对施镀前后基体和镀层的形貌、显微硬度和耐蚀性等进行了表征分析。结果 AZ91HP镁合金经H3PO4+Na3PO4酸洗+NH4HF2活化的无铬处理后施镀，形成的细小胞状组织均匀致密，结合力良好，镀层结构以非晶态相为主，耐腐蚀性比基体显著增高。经热处理后，镀层的硬度明显增高且在400 ℃时获得的镀层硬度最高，但耐蚀性有所下降。 结论 H3PO4+Na3PO4酸洗体系+NH4HF2活化为镁合金提供了一种环保而有效的化学镀前处理方法，获得了以非晶态相为主的Ni-P镀层，提高了基体的耐腐蚀性，镀后热处理可进一步提高镀层的硬度。

The work aims to improve corrosion and wear resistance of AZ91HP magnesium alloy and expand its application scope. H3PO4+Na3PO4 pickling solution and NH4HF2 activated chromium-free pretreatment process was utilized and then electroless plating was performed to obtain Ni-P coating. Later heat treatment was done to the coating. Characterization analysis of morphology, microhardness and corrosion resistance of the substrate and coating before and after plating was performed. Small and compact cellular structures of good adhesion were formed since the AZ91HP magnesium alloy was plated after receiving chromium-free treatment of H3PO4+Na3PO4 pickling solution and NH4HF2 activation. The coating was mainly amorphous. The corrosion resistance was higher than that of the substrate. After heat treatment, microhardness of the coating increased significantly and was the highest at 400 ℃, but the corrosion resistance decreased slightly. The system of H3PO4+Na3PO4 pickling and NH4HF2 activation provides an environmental-friendly and efficient pretreatment process for magnesium alloy. Ni-P alloy coating mainly in amorphous state was obtained, which has improved corrosion resistance of the substrate, and microhardness of the coating could be further improved by heat treatment.