Abstract:The effects of Mg and semi solid processing on the creep properties of A356 Al alloy were investigated. The results show that the dislocation climb controlled creep is the dominant creep mechanism and it is not affected by the semi solid processing and further addition of Mg. Mg improves the alloy creep properties probably by forming large Chinese script Mg₂Si compounds at the interdendritic regions. The semi solid processed specimens exhibit better creep properties in comparison with the as cast ones. It is attributed to the reduction in the stacking fault energy resulting from the significant dissolution of Mg in the α(Al) phase.

Key words: A356 alloy; microstructure; semi solid processing; impression creep; dislocation climb controlled creep