Wear resistance of a laser alloyed A-356 aluminum/WC composite

In this study, the wear resistance of an A-356 aluminum alloy/WC composite obtained by a laser alloying technique has been analyzed. Different laser traversing velocities of 100, 200, 300 and 400 cm min−1 have been used to establish the optimum processing conditions. The interaction time between laser beam and the sample surface, depending on the traversing speed, has a noticeable influence on microstructural morphology and superficial composition, and, hence, on both wear resistance and wear mechanism. Optical microscopy (OM) and scanning electron microscopy (SEM) techniques were used to examined the morphology of treated samples and the corresponding microstructural changes. Wear properties were studied under a load of 5 N by using the ball-on-disk tribometer. The static partners were WC+6% Co balls of 6 mm diameter and the sliding speed used during the test was 0.1 m s−1. Although the friction coefficient values were approximately 0.6 for all samples, their dependence on the sliding distance was quite different for each set of processing parameters. The OM together with SEM techniques were used to elucidate the wear mechanism. It was shown that the WC particles from the composite material had an abrasion action on its counterpart, and this action was observed to decrease with decreasing particle size, which again was a consequence of the increased interaction time between laser beam and substrate. It was concluded that the incorporation of WC hard particles in the A-356 aluminum base alloy was not beneficial from the point of view of wear resistance. For example, for traversing velocities between 300 and 100 cm min−1, there was no significant difference between the wear rates of both unalloyed and WC-laser alloyed A-356 aluminum alloy against a WC ball. For the samples laser treated with 400 cm min−1, a smaller wear resistance was obtained when compared to the untreated samples.