Exceeding average rule of mixtures stiffness in composite materials with interconnected fibres as reinforcement

Abstract

In the present study, a galvanised iron wire mesh structure of two different types was used to reinforce aluminium alloy 1050. The composite was synthesised using conventional casting followed by hot extrusion. Microstructural characterisation of the composite specimens showed good interfacial integrity between the matrix and the reinforcement wire. Thermomechanical analysis demonstrated that the average coefficient of thermal expansion of the composites was decreased below the values predicted by theoretical models. Tensile tests conducted on the composite specimens revealed that the average elastic modulus of the composites exceeded the rule of mixtures predictions. The average values of 0.2% yield strength and ultimate tensile strength of the composites were found to be higher than those of the monolithic aluminium alloy irrespective of a low volume fraction (0.049) of reinforcement. This unusual variation in the properties clearly reflects the uniqueness of using interconnected wires as reinforcement in the metallic matrix. An attempt is made in the present study to rationalise particularly the tensile behaviour, especially the stiffness of the composite material, according to the type of reinforcement preform in the aluminium alloy matrix.