The use of thermodynamic simulation for the selection of hypoeutectic aluminum–silicon alloys for semi-solid metal processing

Currently, established hypoeutectic aluminum–silicon foundry alloys such as aluminum A356 and 357 alloys are also used for semi-solid metal (SSM) processing. Process inconsistencies arising from the use of these alloys are partly due to variations in the fraction solid due to temperature variations. Consequently, the process would be more robust if the alloys were tailored such that the fraction solid variation in the temperature range of operation was minimized. For this purpose, thermodynamic simulations have been carried out to determine the fraction solid and fraction solid variation of hypoeutectic aluminum–silicon alloys as a function of processing temperature, process temperature variation, and silicon and magnesium composition. The fraction solid variation is calculated over a composition range that includes A356 and 357 alloys, and alternate and more desirable fraction solids and alloy compositions that maximize the processing temperature window are suggested for SSM processing.