Grain refinement mechanism of Al-5C master alloy in AZ31 magnesium alloy

Al-5%C master alloy was prepared by powder in situ synthesis process, and its effects on grain refinement of AZ31 alloy and refining mechanism were investigated. The results indicate that the Al-5C master alloy consists of α(Al) and Al4C3 phases, and the size distribution of Al4C3 particles is controlled by sintering time. The Al-5C master alloy can remarkably reduce the grain size of AZ31 alloy, which decreases with the increasing addition amount of Al-5C master alloy when the addition amount is below 2%. The refining mechanism is attributed to the formation of new compounds of Al-C-Mn particles by Al4C3 and Mn, which might act as nucleating substrates for α-Mg grain.