Processing and mechanical properties of Al, A-Mg-2 and Al-Cu-4 alloy base short steel fibre reinforced composites prepared by vortex method

Abstract

In the present work commercially pure Al, Al-2Mg and Al-4Cu alloy base short steel fibre reinforced composites were prepared by vortex method, and poured into cast iron mould. The steel fibres were coated with copper and nickel by electroless deposition techniques to avoid intermetallic formation and improve wettability. The microstructure observation revealed almost uniform fibre distribution with random orientation in matrixes. Density and hardness increased with addition of short steel fibres. Density measurement shows some interesting aspect on the influence of the coating. Coating with copper gives the best fibre distribution among composites with minimum porosity. Mg addition gives better fibre distribution because it reduced surface energy of steel fibre. Alloying element such as copper addition to the matrix improved hardness but increased porosity. The mechanical properties of these composites were measured and the results were correlated with the observed microstructure; the copper coated short steel fibre reinforced composites showed maximum improvement in strength with good ductility. Fracture surface of tensile specimen was examined under SEM, which revealed fracture mechanism dominated by dimple formation and fibre pull-out. Copper coating on steel fibre improved mechanical properties owing to better interface bonding. Mg and copper addition to the matrix helps to improve strength of different fibre reinforced composites with reduce ductility.