2021 年 68 巻 10 号 p. 422-427
20/0/20 vol% Al2O3/Mg laminated spark plasma sintering compacts (20/0/20 vol% laminated SPS compacts), which were fabricated by mechanical milling / SPS method, have proved to possess lightweight like that of general practical Mg alloys and higher surface hardness than them. Moreover, the “diffusion layer” formed at their 0/20 vol% layer interface has been found to exhibit high adhesion to the 20 and 0 vol% layers. The microstructures and the characteristics of “diffusion layer” were investigated using EPMA, XRD and so on. From the results of XRD, the constitutive phases were identified as αMg and MgO. From the results of microstructure observation and elemental analysis using EPMA at the cross section, the microstructures were presumed to be Al solid-solved αMg and needle-like Mg17Al12 generated along the grain boundary of αMg in the mesh-shaped MgO. The cross-sectional hardness was 145 to 155 HV and was higher than that of the AZ91D Mg alloys. The width grew almost linearly rather than parabolic with the passage of sintering time. It is considered that the solid-state reaction of Mg and Al2O3 was promoted with the passage of the sintering time, and the amount of Al dissolved from Al2O3 increased, so that the diffusion amount of Al increased.
