OPTIMIZATION OF HEAT-TREATMENT CONDITIONS OF ALUMINUM SILICON ALLOYS

Results are presented of investigations of the structure, phase compos ition, and mechanical properties of the AL4S alloy after heat treatmen t under various conditions. It is shown that the differences in proper ties in sections of castings cooled at various rates during crystalliz ation are related to changes in the solubilities of the basic alloying elements in alpha-Al and beta-Si solid solutions and their redistribu tion during homogenization before quenching. An optimum set of heat-tr eatment conditions is offered, which produces high levels and stabilit y of properties in castings of various thicknesses.