Tensile and wear-properties of rolled Al5Mg-Al2O3 or C particulate composites

Al5Mg alloy matrix composites reinforced with different percentages of Al2O3 (60 mum) or C (90 mum) particulates were prepared by the vortex method. The composites were then subjected to hot or cold rolling with different reduction ratios. The microstructures of the rolled composites revealed that the matrix grains moved around the particulate causing deformation. By continuing deformation, the particulates rearranged themselves in the matrix, leading to lensoid distortion. It was found that the addition of Al2O3 or C particulates increased the 0.2% proof stress and reduced both the tensile strength and ductility, compared with the monolithic alloy. Scanning electron microscopy (SEM) fractographic examinations showed that the composites reinforced with Al2O3 particulates failed through particulate fracture and matrix ligament rupture. However, the failure of the composites reinforced with C particulates was through particulate decohesion, followed by ductile failure of the matrix. Abrasive wear results showed that the wear rate of the Al5Mg alloy decreased with the addition of C particulates. However, increasing the volume fraction of C particulates did not have a prominent effect on the wear rate. The composites reinforced with Al2O3 particulates exhibited a higher wear rate than that of the unreinforced alloy. Furthermore, addition of both C and Al2O3 particulates into the Al5Mg matrix alloy did not significantly improve the wear resistance. For all composites studied in this work, hot or cold rolling had a marginal effect on the wear results.