Scanning electron microscopy study of worn Al-Si alloy surfaces

A pin-on-disc machine was used to wear Al-Si alloy pins under dry conditions. Unmodified and modified binary alloys and commercial multi-component alloys were tested. The surfaces of the worn alloys were examined by scanning electron microscopy to identify distinct topographical features to aid elucidation of the mechanisms of wear

Erosion of A356 Al−SiCμAl-SiC_{\mu} composites due to multiple particle impact

Solid particle erosion of A356 and the A356-10 vol.% SiCp composite were investigated at room temperature, The composites were fabricated by the melt stir technique and billets were hot extruded. Erosion tests were conducted on these extruded materials with and without T6 treatment. Effect of an excess addition of 0.4% magnesium to the A356 alloy and its composite were also investigated. Tests were performed at three velocities (18, 28 and 50 m s(-1)) and at three impact angles (15 degrees, 30 degrees and 90 degrees). Quartz particles of average sizes 40 mu m and 600 mu m were used as erodents. The eroded surface and the subsurfaces were studied using scanning and optical microscopies. In general, the erosion resistance of the composite is comparable to that of the unreinforced alloy. The present study indicates that the erosion characteristics of the composite are affected mainly by bonding between the reinforcement particle and the matrix, and the size of the erodent particle. The general erosion mechanisms observed in the matrix for both the base alloy and the composite are plastic deformation, gouging and cutting. However, in the case of the composite, additional processes such as fragmentation and removal of SiC occur with impact of coarse particle. Microchipping and protection of the matrix by SiC particles occur for fine size erodent particles