LAUSR

ABSTRACT The laser surface melting was used to improve the microstructure and tribological behaviour of the AZ31B magnesium alloy. The microstructure from the bottom to the surface of the fused layer is bulky dendrites, fine cellular dendrites and finer equiaxed crystal. The grain size of fused layers is increased with the increase of laser power, but it is finer than that of substrate. The phase of the substrate and fused layers are α-Mg and β-Mg17Al12. When the laser power is 2000 W, the content of β-Mg17Al12 reaches the maximum. After laser surface melting, fused layers have higher dislocation density, the shape of β-Mg17Al12 phase becomes uniform spherality, and the size of β-Mg17Al12 phase is about 20 nm. The grain size, dislocation density, β-Mg17Al12 content and distribution et c. improved the wear resistance of AZ31B magnesium alloy. When the laser power is 2000 W, the wear resistance of the fused layer achieves the optimal value.