Microstructure and wear properties of laser surface-cladded Mo-WC MMC on AA6061 aluminum alloy

The creation of a wear-resistant surface of metal matrix composite on AA6061 aluminum alloy by laser surface melting of pre-pasted Mo-WC powder was successfully achieved using a 2-kW CW Nd-YAG laser. A high-quality coating without porosity or cracking was obtained. Excellent bonding between the coating and the aluminum alloy substrate was ensured by the strong metallurgical interface. Different ratios of Mo and WC powders were investigated. The chemical composition, microstructure and surface morphology of the clad layer were analyzed using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffractometry (XRD). The surface hardness of the Al specimens clad with Mo/WC is increased seven-fold. The samples have been characterized with abrasive pin-on-disc wear tests. The test results show that the composite coating with a WC hard phase has improved abrasive wear resistance when compared with the as-received A] substrate. The wear mechanism of the specimens is discussed based on microscopic observation of the worn surface. (C) 2001 Elsevier Science B.V. All rights reserved.