Coarsening Kinetics of Semi-solid A356–5wt%TiB2 in situ Composite

摘要

An attempt has been made to investigate the coarsening behaviour of semisolid A356–5wt%TiB2 in situ composite produced by Cooling slope casting. It was found that the average grain size of α-Al in the gravity-cast alloy got reduced from 98 to 48 µm in the semi-solid A356–5TiB2 composite. The primary α-Al in the composite were found to undergo substantial spheroidisation after 5 min at a reheating temperature of 585 °C (f s  = 0.5). Further, increase in holding time from 5 to 15 min resulted in grain growth of α-Al in both the alloy and the composites. The coarsening rate constant, K, for A356–5wt%TiB2 composite was found to be 339.73 μm3/s which is 32 % lower than that of semi-solid A356 alloy, thus proving the effectiveness of TiB2 particles towards grain coarsening.