Effect of pouring temperature on cast Al/SiCp and Al/Ti B2 metal matrix composites

The effect of pouring temperatures of an ex situ (Al/SiCp) and in situ (Al/TiB2) 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 degrees C, 750 degrees C and 770 degrees C). The Al/TiB2MMCs were obtained by melting A356 aluminium alloy and mixing of KBF4 and K2TiF6 precursor salts whose stoichiometric ratio composition corresponds to 6wt.% of TiB2 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 degrees C, 820 degrees C and 840 degrees C). Coarser and homogenous SiC particles were presented in the Al/SiCp MMCs, whereas, finer and uniformly distributed TiB2 particles were appeared at the MMCs of Al/TiB2. The mechanical properties viz. tensile strength, fracture toughness and hardness of Al/SiCp and Al/TiB2 MMCs were experimentally determined as per the ASTM standards and compared. Higher tensile and fracture strength were occurred at the MMCs of Al/TiB2 as compared to Al/SiCp MMCs and base alloy of aluminium as well. Maximum hardness was attained at the pouring temperatures of 820 degrees C and 750 degrees C in the MMCs of Al/ TiB2 and Al/SiCp, respectively.