Phase equilibria and solidification of Mg-rich Al-Mg-Si alloys

The solidification and solid-state phase equilibria of four Al-Mg-Si alloys containing 30-70%Mg and 0.5-3.5%Si, selected on the basis of an isothermal section of the Al-Mg-Si system calculated at 300 degrees C, have been investigated. Solidification paths of Mg-rich Al-Mg-Si alloys finish on ternary eutectics and the temperatures of two of these eutectic reactions, i.e. L <->(Al)+beta+ Mg(2)Si and L <->(Mg)+gamma+ Mg(2)Si, have been determined to be at similar to 448 degrees C and similar to 436 degrees C respectively by DTA. The characteristic temperatures recorded on the DTA curves are analysed and a linear relationship is found between the peak temperature and the square root of the scanning rate.