Influence of coating and alloy additions on distribution of fibres and hardness of cast aluminium base short steel fibre reinforced composites

Abstract

In the present investigation, the effect of copper and nickel coating on the steel fibre and alloying addition on fibre distribution in Al, Al–2Mg and Al–4Cu alloy matrix composites was investigated experimentally. Short steel fibres reinforced composites were prepared through stir casting process and cast into a cast iron dies. An attempt is made in this study to establish the trend between processing parameters such as coating on the fibre and alloying addition with microstructure, density and hardness of composites. Fibre distribution in the cast composite along longitudinal and transverse direction was determined by sectioning several locations and microstructure, density and hardness investigation techniques. The results revealed that coating on the fibre and alloying addition influenced the fibre distribution in composites. The regions close to the top, bottom and the boundary wall were determined as the fibre segregation areas. Microstructure observation revealed that variation in fibre volume fraction was less in the case of copper coated fibre reinforced composite. Also Al–2Mg base composites reduced the variation of fibre volume fraction. The density and hardness value followed a similar pattern. Density and hardness values were higher at the top, near the side wall and bottom of the plate. Alloying with copper and coating with nickel increased the variation of hardness and density. Copper coating on the fibres as well as alloying with magnesium reduced the variation in fibre distribution. The more uniform fibre distribution was achieved in case of copper coated fibre reinforced composite.