Effect of alloy elements added on microstructure and hardening of Al/SiC laser clad coatings

Al/SiCp coatings were deposited on AA6082 aluminum alloy using a laser cladding process. The SiC particles tend to dissolve and react with aluminum to form detrimental Al4C3 and a strategy has been developed to avoid this problem. The method employed consists of the addition of different alloying elements (Si or Ti) to the composite matrix powder to modify the equilibrium of the Al4C3 formation reaction. Different percentages of Si were tested and the formation of Al4C3 was totally inhibited when the percentage of silicon was higher than 40 wt.%. The addition of Ti particles to the composite matrix also inhibited the formation of Al4C3. The coatings microstructures were analyzed by optical microscopy and scanning electron microscopy. The effect of the laser control parameters on the coating geometry, coating-substrate interface and adhesion has been analyzed. The coatings mechanical properties were measured using microhardness and nanoindentation techniques.