Friction and wear characteristics of Mg-11Y-2.5Zn magnesium alloy treated by laser surface melting

摘要

An attempt has been made to enhance the tribological properties of Mg-11Y-2.5Zn alloy by lasersurface melting with a 6 kW continuous wave CO_2 laser processing system. The microstructureand microhardness of the surface layer on Mg-11Y-2.5Zn alloy were characterised using X-raydiffractometer, laser microscopy and Vickers hardness indentation. The laser surface melted zoneconsisted of fine dendrites and coarse dendrites growing epitaxially from the liquid/solidinterface. Microhardness was improved from 69-70 HV for the substrate to 77-83 HV for the finedendritic microstructure. The friction and wear characteristics were investigated using a pin ondisc apparatus. The coefficient of friction curve of the laser surface melted specimen was similarto that of the untreated specimen. Laser surface melted Mg-11Y-2.5Zn alloy exhibited good wearresistance, which has been explained by refinement of microstructure in the melted zone. Fourwear mechanisms including abrasion, delamination, thermal softening and melting, have beenobserved.