Characterisation and mechanical properties of Al/SiC metal matrix composite coatings formed on ZE41 magnesium alloys by laser cladding

Abstract

Metal matrix composite coatings on light alloys are in high demand in the transport industry to reduce the weight of vehicles without a reduction in mechanical properties. Composite coatings with various mixtures of Al, Si, Ti and SiC could be a good option for this application but the high reactivity between the melted aluminium and the reinforcement must be avoided. This study provides a solution for this problem for laser cladding composite coatings on ZE41 magnesium alloys. The method employed consists of the addition of different alloying elements (silicon or titanium) to the composite matrix to avoid Al4C3 formation. A dilution of magnesium from the substrate in the aluminium coating matrix takes place and it produces an important effect in the matrix-reinforcement reactions. The microstructure and mechanical properties of the coatings are analysed. The reaction mechanisms are also determined. Al4C3 formation is avoided and the mechanical properties are improved. Keywords: Metal matrix composites, Coating materials, Laser processing, Microstructure, Scanning electron microscopy (SEM)