Structure and mechanical properties of composite layers prepared by laser alloying of aluminium alloy

Increasingly high expectations for modern engineering, make the constantly being sought-after new processes giving traditional materials new, better features. Nowadays, next to the standard heat treatments, advanced technologies are being used increasingly, leading to much better results than ever before. The most commonly used technologies that allow for obtaining new, enhanced properties of various metal alloys in the area of surface engineering include, among others laser surface treatment. The main objective of this paper was to analyze the influence of laser surface treatment on structural change and mechanical properties improvement of Al-Mg alloy by VC alloying. The remelted layer on the aluminium alloy surface was obtained using high power fiber laser “Ytterbium Laser System YLS-4000". The surface sample was remelted using a rectangular laser beam (2 × 4mm) with a power of 3kW (1.53e+4W/cm²). The scanning speed of the laser beam was 0.8cm/s (0.48m/min). The remelting area has been protected by the use of technical argon blowing. During the process, sintered particles of vanadium carbide with an average size of about 50-100µm was introduced into the liquid metal. Ceramic powder in the remelting volume was fed with a pressure feeder (constant rate of 5 g/min). As a substrate, the ENAC AlMg3 alloy has been used. During the laser treatment, a composite layer with much better mechanical properties was obtained comparing the base material. The average hardness of the layer was about 19 HV_0.1 higher than that of the base material. Chemical analysis, carried out with the EDS (energy dispersive spectroscopy) detector and transmission microscope revealed many undissolved powder particles used in the alloying process, as well as those of Al₈V₅, precipitated in the Al-Mg matrix.