Nawal Ezzat; Nada Taher Sultan
Abstract
Semi-solid metal processing involves processing metallic alloys between thesolidity and the liquidity. The microstructure must be non-dendritic and consist ofspheroids of solid in a ...
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Semi-solid metal processing involves processing metallic alloys between thesolidity and the liquidity. The microstructure must be non-dendritic and consist ofspheroids of solid in a liquid matrix. In this work two potential routes are used:First, The superheated Al-Si-Mg alloy was continuously cooled down to varioustemperatures above its liquidity (620,630,640) o C . When the desired temperature ofthe melt has been reached, then mechanical stirring with rotational speed of(800)rpm for (30)sec. was started. The resultant slurry was bottom poured into astainless steel mold placed below the crucible. The solidified samples were reheatedto the semi-solid metal processing temperature, held there for (10) min, and rapidlyquenched in into water tank to retain the semi solid microstructures. In the second setof experiments , the superheated melt was continuously cooled down to varioustemperature in semi solid range (610,600,595,590,580)o C, then mechanically stirredat rotating speed(800)rpm for (30)sec. the resultant slurry was bottom poured into astainless steel mold placed below the crucible. The metallic mold is then rapidlyquenched in water to room temperature. Metallographic examinations indicate thatthe mixing method leads to highly globular semi-solid slurries of fine particle size.The particle sizes of slurry quenched at various temperatures within the semi solidmetal range are much smaller when compared to the reheated structures. The particlesize gradually increases as the slurry temperature decrease.
