Influence of mould thickness on microstructure, hardness and wear of Al-Cu cast alloys

Abstract

Aluminium-copper alloys have a wide range of industrial applications especially in military vehicles, rocket fins and aerospace. Solidification plays a vital role in controlling the mechanical and tribological properties, and influencing the microstructure of metallic alloys in general and aluminium alloys in particular. Therefore, the researchers have made many efforts to figure out the solidification behaviour of Al-Cu alloys. Despite all these endeavors, however, the behavior is not yet fully understood. This research aims to investigate the effect of cooling rate on the microstructure, mechanical and tribological properties of aluminium-copper cast alloys (Al-Cu alloys) under dry sliding conditions. Four cooling rates were achieved by using four various steel moulds made of different thicknesses and one of them was surrounded with green sand, to get a lower cooling rate, with the same respective mould hole geometries. The microstructure results showed that the grain size increases with decreasing the cooling rate. While the hardness increased largely due to the refinement of the microstructure. Finally, it was concluded that the wear rate increases with decreasing the cooling rate, and that is due to the reduction in hardness.