Mechanical testing and machinability study of aluminium hybrid metal matrix using laser beam machining

Abstract

Hybrid Metal Matrix Composites (HMMCs) have recently developed as composite materials through the addition of aluminium with ceramic particles. Compared to other metals and alloys, the major benefits of HMMCs are improved properties such as superior wear properties, better strength to wear ratio, high modulus, high-temperature resistance and better corrosion resistance. These properties have enabled their use in aerospace, automotive, electronics and consumer goods. However, HMMCs have limited applications due to their low machinability. Different hard reinforcement particles are added to the matrix for the improvement of the properties and machinability of HMMCs. Reinforcement particles including silicon nitride, boron, silicon carbide, silica sand, magnesium oxide, glass beads, titanium carbide and boron carbide are added to the matrix. The B4C, SiC and Al2O3 are mixed effectively to the molten aluminium. Hence, SiC is selected as one of the reinforced materials. Among the various reinforcement particles, Zirconium silicate is also identified as promising reinforcement, due to its high melting point and refractoriness and its high resistance to abrasion, impact and sudden volume changes at elevated temperatures. Hence, ZrSiO4 is selected as another reinforcement for the matrix. Literature shows the adoption of micron level square holes in HMMCs as in the aerospace industry and in various instruments due to their special mechanical properties. Yet, the fabrication of micro square holes is a more difficult task than machining round holes because of the corner radius problem. Square holes are fabricated using mechanical drilling, electrochemical machining and electrical discharge machining. newline