Hardfacing of aluminium alloys by means of metal matrix composites produced by laser surface alloying

Abstract

Metal matrix composite layers were formed on an aluminium substrate by means of laser surface alloying method. Aluminium 1200 was used as a host material and TiC particles were used as the reinforcement. The microstructure of the modified layer consisted of the hard particles uniformly distributed in the host metal matrix. A strong bond between the particles and matrix was formed in the modified layer. A Rofin Nd: YAG laser was used for injecting the ceramic powder into the substrate. In these experiments the laser power was varied from 3 to 4.0 kW, the laser scan speed was varied from 0.8 to 2.0 m/min. The powder feed rate was varied from 2 to 5 g/min. The structural characterisation of the metal matrix composite included X-ray diffraction (XRD), optical and scanning electron microscope (SEM) as well as microhardness measurements. The microhardness of the layers increased from 20 HV to 350 HV. This represented a significant improvement of the surface properties compared to the base metal.