Effect of heat treatment on microstructure and wear behavior of Al–Si alloys with various iron contents

Effect of T6 heat treatment on microstructure and wear behavior of hypoeutectic Al–Si alloys with iron contents of 0.15, 0.7 and 1.2 wt% was studied. Dry sliding wear tests were performed on a pin-on-disk tribometer under normal loads of 20, 30 and 40 N. The alloy with 0.7 wt% iron showed the highest wear resistance before the heat treatment under the loads tested. T6 heat treatment improved the wear resistance of the alloys with different iron contents compared to the non-heat treated 0.7 wt% iron alloy under all applied loads. The improvements in the wear can be attributed to the decrease of length and volume fraction of hard and brittle β-Al5FeSi iron-rich intermetallics and spherodization of the coarse eutectic silicon particles by diffusion of iron and silicon into the matrix upon solution heat treatment. The change in the morphology of the phase particles reduced the probability of nucleation and propagation of subsurface cracks and increased the wear resistance in the samples.