Simplified rheocasting of Al-Si alloys sheared by mechanical stirring

A rheocasting prototype for the semi-solid processing of Al-Si alloys was designed and assembled at laboratory scale, this is the first attempt for the development of S2P equipment in Mexico. This work describes the simplified method of mechanical stirring and the calculation of the theoretical parameters for the operation of the experimental device in order to provide shear rate into the slurry by a stainless steel impeller inside a crucible made of hot work steel. This paper presents a new design of rheocasting equipment. Moreover, a vertical pressure die-rheocasting system it is applied with the semi-solid alloy flowing counter the position of the injector during the displacement of the crucible in order to fill the mold. The semi-solid state with thixotropic behavior was produced in stirred AlSi7Mg alloy. The nondendritic morphology was arrived at via the intensive stirring at the beginning of the solidification. This process produces the trimming of dendrites, growing so the primary solid (α) in globular shape surrounded by eutectic microstructure. The semi-solid material was solidified in the mold and preliminary microstructural characterization was performed.