Effect of spheroidization heat treatments on the hardness of Al-Si alloys

In order to modify the as-cast structure of Al-Si alloys with 12, 14 and 20% wt. Si, spheroidization heat treatments were carried out. The modification of size, form, disposition and distribution of silicon crystals (both primary and eutectic) have been studied by optical microscopy. The variation of the mechanical properties, as a consequence of the heat treatment, was determined by measuring the hardness. It has been found that the spheroidization heat treatment improves the mechanical properties of the alloys under study. (author)