Processing and characterization of the microstructure and mechanical properties of Al6061-TiB2 composite

In the present research, aluminum metal matrix composites were processed by the stir casting technique. The effects of TiB2 reinforcement particles, severe plastic deformation through accumulative roll bonding (ARB), and aging treatment on the microstructural characteristics and mechanical properties were also evaluated. Uniaxial tensile tests and microhardness measurements were conducted, and the microstructural characteristics were investigated. Notably, the important problems associated with cast samples, including nonuniformity of the reinforcement particles and high porosity content, were solved through the ARB process. At the initial stage, particle-free zones, as well as particle clusters, were observed on the microstructure of the composite. However, after the ARB process, fracturing phenomena occurred in brittle ceramic particles, followed by breaking down of the fragments into fine particles as the number of rolling cycles increased. Subsequently, composites with a uniform distribution of particles were produced. Moreover, the tensile strength and microhardness of the ARB-processed composites increased with the increase in the reinforcement mass fraction. However, their ductility exhibited a different trend. With post-deformation aging treatment (T6), the mechanical properties of composites were improved because of the formation of fine Mg2Si precipitates.