The feasibility of semi solid processing of hypereutectic A390 alloys using a novel rheoforming process was investigated.A combination of the swirl enthalpy equilibration device (SEED) process, isothermal holding using insulation and addition of solid alloy during swirling was introduced as a novel method to improve the processability of semi solid slurry.The effects of isothermal holding and the addition of solid alloy on the temperature gradient between the centre and the wall and on the formation of α(Al) particles were examined.In additional tests, phosphorus and strontium were added to the molten metal to refine the primary and eutectic silicon structure to facilitate semi solid processing.The results show that the combination of the SEED process with two additional processing steps can produce semi-solid A390 alloys that can be rheoprocessed.The microstructure reveals an adequate amount of non-dendritic α(Al) globules surrounded by liquid, which greatly improves the processability of semi-solid slurry. The feasibility of semi solid processing of hypereutectic A390 alloys using a novel rheoforming process was investigated. A combination of the swirl enthalpy equilibration device (SEED) process, isothermal holding using insulation and addition of solid alloy during swirling was introduced as a novel method to improve the process of of semi-solid slurry. The effects of isothermal holding and the addition of solid alloys on the temperature gradient between the center and the wall and on the formation of α (Al) particles were examined. Additional tests, phosphorus and strontium were added. to the molten metal to refine the primary and eutectic silicon structure to semi-solid A390 alloys. The results show that the combination of the SEED process with two additional processing steps can produce semi-solid A390 alloys that can be rheoprocessed. amount of non-dendritic α (Al) globules surrounded by liquid, which greatly improves the processabil ity of semi-solid slurry.