Wear behaviour of cast and mushy state rolled Al-4.5Cu alloy and in-situ Al4.5Cu-5TiB2 composite

Dry sliding wear behaviour of as cast, mushy state rolled Al-4.5(wt.%)Cu alloy and in situ Al-4.5(wt.%)Cu-5TiB2 composite has been studied. Mushy state rolling has been performed on the cast alloy, and as cast or pre-hot rolled composite at temperatures corresponding to 10, 20 or 30 vol.% liquid to reduction in thickness of 2.5, 5 or 7.5%. Wear tests carried out at loads of 19.6, 39.2, 58.8, and 78.4 N on a pin-on-disc machine, have shown that both the mushy state rolled alloy and composite are more wear resistant than their as cast samples. The wear rates decrease with increasing hardness, with the exception of as cast alloy. For 7.5% reduction, the wear rate is the least in the samples rolled at temperature for 20 vol.% liquid. The specific wear rate, as well as the wear and friction coefficients have been evaluated from wear data to understand the roles of sub-surface plastic deformation and work hardening on wear behaviour. Examination of the wear surfaces and cross-sections as well as the wear debris suggests that wear involves removal of softer Al as flakes and transfer of Fe from the steel disc to the surface of the composite pin.