ALUMINUM ALLOY CASTING MATERIAL FOR HEAT TREATMENT EXCELLING IN HEAT CONDUCTION AND PROCESS FOR PRODUCING THE SAME

摘要

An aluminum alloy casting material for heat conduction obtained by adding Si to an aluminum alloy casting material with enhanced castability to thereby realize enhancement of thermal conductivity. There is provided an aluminum alloy casting material excelling in heat conduction, characterized in that it comprises 5 to 10.0 mass% of Si, 0.1 to 0.5 mass% of Mg and the balance of Al and unavoidable impurities, the aluminum alloy casting material having undergone an aging treatment. Further, there is provided a cast aluminum alloy casting material that while having castability and mechanical strength equivalent to or higher than those of conventional cast aluminum alloys, is also enhanced in heat conduction; and provided a process for producing the cast aluminum alloy. In particular, there are provided a cast aluminum alloy and process for producing the same, wherein Si is contained in an amount of 6.0 to 8.0 mass%, the elements other than Si and Al each in simple form in an amount of ≤ 0.6%, and wherein the amount of Si solid-dissolved in aluminum parent phase is regulated to 0.5-1.1 mass% while the area ratio of crystallizate in metal structure is regulated to 5-8%. In this connection, the amount of Si solid-dissolved and the area ratio of crystallizate can be attained by performing of heating retaining treatment of the subject matter of cast aluminum alloy after casting operation at 400˚ to 510˚C for ≥ 1 hr.