Effect of pouring temperature on cast Al/SiCp and Al/TiB ₂ metal matrix composites

The effect of pouring temperatures of an ex situ (Al/SiCp) and in situ (Al/TiB 2 ) metal matrix composites (MMCs) synthesized using stir casting method were studied. The Al/SiCp composite were fabricated by mixing of 6wt.% of SiCp into cast A356 aluminium alloy melt and poured at diverse pouring temperatures (730 ∘ C, 750 ∘ C and 770 ∘ C). The Al/TiB 2 MMCs were obtained by melting A356 aluminium alloy and mixing of KBF 4 and K 2 TiF 6 precursor salts whose stoichiometric ratio composition corresponds to 6wt.% of TiB 2 reinforcement and other parameters were constant (stirring speed 300 RPM and holding time 30 minutes). The composite melt was poured into the permanent mould with varied pouring temperatures (800 ∘ C, 820 ∘ C and 840 ∘ C). Coarser and homogenous SiC particles were presented in the Al/SiCp MMCs, whereas, finer and uniformly distributed TiB 2 particles were appeared at the MMCs of Al/TiB 2 . The mechanical properties viz. tensile strength, fracture toughness and hardness of Al/SiCp and Al/TiB 2 MMCs were experimentally determined as per the ASTM standards and compared. Higher tensile and fracture strength were occurred at the MMCs of Al/TiB 2 as compared to Al/SiCp MMCs and base alloy of aluminium as well. Maximum hardness was attained at the pouring temperatures of 820 ∘ C and 750 ∘ C in the MMCs of Al/ TiB 2 and Al/SiCp, respectively.