Mlcrostructure and Corrosion Resistance of Electroless Ni-P Alloy Coating on the Surface of Magnesium Alloy

Bright,uniform and compact electroless Ni-P alloy coating with a thickness of 40 μm was fabricated on the surface of AZ91D Mg alloy substrate.Themicro-appearance,composition,micro-hardness,adhesive force and corrosion resistance of the Ni-P coating were investigated.Results show that the Ni-P alloy coating with a moderate content of P has cystiform micro-appearance and microlite mierostructure.Besides,the Ni-P alloy coating had good adhesion to the sub-strate.Its microhardness was 5 times as much as that of the sub-strate,while its corrosion resistance was better than that of the substrate as well.