Effect of microstructure and residual stresses on nano-tribological and tensile properties of Al2O3- and SiC-reinforced 6061-Al metal matrix composites

Abstract

In this investigation, wear and tensile properties of 6061-Al/Al2O3 and 6061-Al/SiC metal matrix composites were studied with respect to their microstructural features and residual stresses. Variation in the residual stress values in the composites differed from each other due to their particulate size and thermal expansion coefficient. Tribological behavior of the composites studied with the aid of nanoscratch tester showed higher amount of debris in 6061-Al/SiC composite than that in 6061-Al/Al2O3 composite due to the presence of higher residual stresses and shorter interparticle distance in the former. Variation of wear volume, coefficient of friction and wear rate at different load were analyzed and correlated with the variation of microstructure along the scratch tracks. It is seen that wear resistance of 6061-Al/Al2O3 is better than that of 6061-Al/SiC composite, where as tensile property revealed that ultimate tensile stress and yield stress is higher in case of 6061-Al/SiC composite compared to 6061-Al/Al2O3. Fractographic studies shows bimodal fracture failure where cleavage type brittle fracture failure is dominant in 6061-Al/Al2O3 whilst ductile failure is dominant in 6061-Al/SiC composite.