Effect of laser alloying on heat-treated light alloys

Abstract

Abstract This paper presents the results of a microstructure and hardness investigation into the surface layer of cast aluminium–silicon alloys, after being alloyed by heat treatment and/or remelted with ceramic powders, using a high power diode laser (HPDL). The purpose of this work was to determine the appropriate laser treatment conditions for laser surface treatment of the investigated aluminium and magnesium alloys. For investigation of the obtained structure, optical and scanning electron microscopy was used with energy dispersive X-ray spectroscopy microanalysis. After the laser surface treatment was carried out on the heat-treated aluminium and magnesium cast alloys, there were visible structural changes concerning the microstructure, as well as distribution and morphology of the phases occurring in the alloy, influencing the hardness of the achieved layer. In the structure, three zones were discovered with different structures and properties. Concerning the laser treatment conditions for laser-surface hardening, the laser power and ceramic powder feed rate were also studied. The structure of the surface laser track changed so that two areas of the dispersing zone were detected, where the ceramic powder particles were present. This investigation, with the application of an HPDL for Al and Mg alloys, makes it possible to obtain or develop an interesting technology that is very attractive for the automobile and aviation industries, as a next step after laser surface treatment used for steels.