EFFECT OF HEAT TREATMENT ON METALLURGICAL AND MECHANICAL PROPERTIES OF AN ALUMINIUM 6061 HYBRID COMPOSITE

Aluminium hybrid metal matrix composites (Al-HMMCs) are fabricated to investigate the influence of heat treatment on metallurgical and mechanical properties. Aluminium 6061, known for its heat treatability and versatile applications is used as the base material, and it is reinforced with tungsten carbide nanoparticles and graphite. Stir casting is used for fabricating four composite samples. The prepared samples are subjected to a microscopic analysis and mechanical testing. The microscopic analysis shows segregation along the grain boundaries, which are refined upon heat treatment. FESEM images with EDX mapping reveal an even distribution of reinforcement particles without any agglomeration. Two different intermetallic phases are formed in the shapes of plates and scripts, some of which dissolve to form precipitate-resisting grain growth and dislocation movement upon heat treatment, enhancing the mechanical properties. The hardness of heat-treated composites is, on average, 33 % higher than that of non-heat-treated composites. The yield strength and ultimate tensile strength of the heat-treated Al-HMMC are improved by 43 % and 38 %, respectively, compared to the Al6061 alloy. The ductility of Al-HMMC is preserved even with the addition of hard ceramic reinforcement, as evidenced by the percentage elongation of heat-treated Al-HMMC and supported by fractographic analysis.