Abstract:

The microstructure and phase constitution of alloy Mg-11Y-2.5Zn surface modified by melting and resodification by a  6.0 kW continuous wave CO2 laser were analyzed by X-ray diffractometer and laser cofocused SEM, and its hardness change was measured by Vickers. The results revealed that the modified surface layer consists of a melted zone and a heat affected zone, the microstructure in the melted zone is considerably finer with correspondingly higher hardness. The tribological properties of the alloy were investigated in ascast state and after laser treatment under a load range of 20~320 N and a sliding velocity of 0.785 m/s on a tester with a pinondisc configuration. The results show that there was no obvious difference in their friction factors, but the laser surface treated alloy exhibited better wear resistance due to finer microstructure and higher hardness. The morphology analysis of the worn surfaces by SEM showed that their wear mechanism is basically the same, in the light wear stage the dominant are the abrasive and peeling wear, and in the serious wear stage are wear due to heat softening and melting of the surface.

Key words: materials synthesis and processing technology;metallic material, magnesium alloy, microstructure, laser surface melting solidi fication, tribological properties