Microstructure and Mechanical Properties of Aluminum Matrix Composites Reinforced With In-Situ TiB2 Particles

The present article investigates the microstructure and mechanical properties of A356 matrix composite reinforced with TiB2 particles synthesized by the salt metal reaction of as-cast and T6 state. Microscopic observations of the prepared composites reveal that in-situ grown TiB2 particles are characterized with regular shapes and nearly uniform distributed in the A356 matrix. A clear interface between the A356 matrix and TiB2 particles was observed. The detailed analysis of mechanical properties of synthesized composites of as-cast and T6 state show that the ultimate tensile strength and Young's modulus of the synthesized composites increased with the increasing weight percentage (wt%) of in-situ TiB2 particles in the A356 matrix, but the Poisson's ratio of the synthesized composites decreased with the increase of TiB2 particles wt%. The Young's modulus of the composites increased by up to 10.8% and the Poisson's ratio decreased by up to 3.2% with the increase of TiB2 particles wt%, compared to A356 alloy. With the increase of TiB2 particle wt%, the yield strength of the composites decreased at first (when the TiB2 particle wt% is less than 1%) then increased, while elongation and percent reduction in area increased at first and then decreased. Furthermore, T6 heat treatment can refine grain and effectively improve the mechanical properties of composites.