Effects of the morphology and content of Al2O3 particles on the microstructure and mechanical properties of cold sprayed Al2O3 /A380 Al alloy composites

In this study, we systematically investigated the effects of the morphology and content of Al2O3 particles on the microstructure and mechanical properties of cold sprayed Al2O3 /A380 Al alloy composites. For this purpose, various fractions (wt.%) of Al2O3 particles with spherical and irregular morphologies were used in the feedstock powder in the order: 0, 10, 20, 30, 40 and 50wt.%, respectively. The as-sprayed composite deposit was characterized by investigating the surface morphology, roughness, porosity, deposition efficiency and microhardness. Results revealed that the addition of spherical alumina particles has a significant tamping effect on the coating, which is manifested in the decrease of surface roughness and porosity of the coating. In contrast, the embedding effect of irregular alumina particles was remarkable. The deposition efficiency of the irregular alumina was much higher than that of spherical alumina particles. Moreover, the roughness of the coating did not change significantly while the porosity slightly increased due to the fracturing of the colliding alumina particles during deposition. Microhardness results revealed that the microhardness of the deposit value increases sharply with increase in the content of irregular alumina particles while it moderately increases with the increase in content of the spherical alumina in the feedstock.