Sliding wear behavior of in situ Al–4.5Cu–5TiB2 composite processed by single and multiple roll passes in mushy state

A comparative study has been carried out on dry sliding wear behavior of in situ Al–4.5Cu–5TiB2 composite subjected to single or multiple mushy state roll passes, each to 5% thickness reduction at 626 °C (temperature for 20% liquid). The results of wear tests using a pin-on-disc machine under normal loads of 20 or 40 N have been analyzed to determine wear rate, friction and wear coefficients. It has been found that wear resistance of rolling surface is superior to that of long-transverse surface, and improves on subjecting composites to higher number of roll passes, which cause enhancement of hardness through grain refinement and particle redistribution. Studies of surfaces and cross-sections of worn specimens as well as wear debris have shown evidence of Fe-enrichment, plastic deformation and work hardening. Surface roughness and friction coefficients depend on wear mechanisms, which appear to be influenced by applied load and specimen hardness.