Microstructure and mechanical properties of high power diode laser (HPDL) treated cast aluminium alloys

The appliance and development of modern technologies in the areas of surface engineering can be extended by laser surface treatment, especially using high power diode laser (HPDL) for remelting, feeding and/or alloying. The purpose of this work was to determine technological and technical conditions for tungsten carbide (WC) ceramic powder feeding into the surface layer of the laser treated Al-Si-Cu cast aluminium alloys with high power diode laser, as well as to investigate the microstructure and ceramic powder particle distribution in the surface layer. Special attention was devoted to monitoring of the layer morphology of the investigated material and on the particle occurred. Light and scanning electron microscopy as well as X-Ray diffraction were used to characterize the microstructure of the remelted zone. A wide range of laser powers was choose and implicated by different process speed rates. Also one powder in form of tungsten carbide was used for feeding with the middle particle size of 80 μm. As the main findings there was found that, the obtained surface layer is without cracks and defects as well as has a comparably higher hardness value compared to the non remelted material. The hardness value increases according to the laser power used so that the highest power applied gives the highest hardness value in the remelted layer. Also the distribution of the tungsten carbide particles is good, but there are still possibilities for further modelling. The major purpose of this work is to study the effect of a high power diode laser melting on the cast Al-Si-Cu alloys structure to provide application possibilities for automotive and aviation industry.