Trial of Surface Coating of Magnesium Alloys with Alumina Particle Dispersed Magnesium Powders

The authors have fabricated spark plasma sintering (SPS) compacts with hardness (>200 HV) exceeding those of practical Mg alloys from 20 vol% Al2O3/Mg (20 vol%) powder with uniform dispersion of Al2O3 particles in Mg using a mechanical milling (MM) method. In this study, for the purpose of surface modification of practical Mg alloy M1A, the properties of M1A laminated compacts with thin 20 vol% layers on the surface of M1A discs fabricated by MM/SPS method were investigated. The surface hardness, lubricity, and wear resistance of the M1A disc were improved by coating the surface of the M1A disc with a highly adherent 20 vol% layer. Based on the results of X-ray diffraction and elemental analysis by SEM-EDS, it is considered that Al diffuses to the M1A disc and Mn diffuses to the 20 vol% layer, resulting in the precipitation of MnAl, an Mn-Al intermetallic compound at the 20 vol% layer/M1A interface. The relationship between the sintering time and the adhesion of the interface was investigated. The results suggest that the amount of Al diffusion from the 20 vol% layer to the M1A disc affects the adhesion of the interface rather than the precipitation of the Mn-Al intermetallic compounds at the interface.