Abstract:By laser multilayer cladding using a pulsed Nd-YAG irradiation the thickness of the cladding zone Mg-based alloys(ZM2 and ZM5) can reach about 1.0mm.The microstructure of the substrate and the cladding zone was studied using optical microscope, scanning electron microscopy(SEM), Xray diffractometry(XRD) and micro hardness analysis. It is observed that constituent of ZM5 alloy is δ+Mg₁₇Al₁₂, that of ZM2 alloy is α+MgZn+Mg₉Ce. That of cladding layer ZM2 alloy(L-ZM2) is Mg+Mg₂Zn₁₁+MgCe; while that of the cladding layer ZM5 alloy(L-ZM5) is Mg+Mg₃₂(Al, Zn)₄₉. The hardness of the cladding area can be increased to values above HV127. Very fine uniform microstructure and the produced new phases of nanometer/sub-micrometer order were obtained. Now, many repaired Mg-based alloy components have been passed by flying test in outside field.

Key words:  laser multi-layer cladding; Mg-based alloys; microstructure; repairing