Aluminum Alloy Casting Material for Heat Treatment Excelling in Heat Conduction and Process for Producing the Same

Abstract

An aluminum alloy casting material for heat conduction obtained by adding Si to an aluminum alloy casting material with enhanced castability 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.

1 . An aluminum alloy casting material having excellent thermal conductivity, comprising 5-10% by mass of silicon, 0.1-0.5% by mass of magnesium, the remainder comprising aluminum and inevitable impurities, and upon which an aging treatment has been performed. 
     
     
         2 . The aluminum alloy casting material having excellent thermal conductivity recited in  claim 1 , further comprising 0.3-0.6% by mass of iron. 
     
     
         3 . The aluminum alloy casting material having excellent thermal conductivity recited in  claim 1 , whereon the aging treatment is maintained for 1-10 hours at a temperature of 160-270 degrees Celsius. 
     
     
         4 . The aluminum alloy having excellent thermal conductivity recited in  claim 1 , wherein, before performing the aging treatment, solution heat treatment is undertaken by holding for 1-10 hours at 480-540 degrees Celsius, and subsequently quenching by cooling to a temperature of 100 degrees Celsius or below at a cooling rate of 100 degrees Celsius per second or faster. 
     
     
         5 . An aluminum alloy casting having excellent thermal conductivity, comprising 6.0-8.0% by mass of silicon, the amount of any single element other than silicon or aluminum being 0.6% by mass or below, the amount of silicon in solid solution within the aluminum matrix being adjusted to 0.5-1.1% by mass, and the area ratio of the crystallized products within the metal structure being adjusted to 5-8%. 
     
     
         6 . The aluminum alloy casting recited in  claim 5 , comprising 6.0-8.0% by mass of silicon, 0.2-0.5% by mass of magnesium, 0.6% by mass or less of iron, the remainder comprising aluminum and other elements, the total amount of other elements being 0.2% by mass or less. 
     
     
         7 . The aluminum alloy casting recited in  claim 5 , wherein the amount of titanium and/or zirconium is adjusted to 0.03% by mass or less. 
     
     
         8 . The aluminum alloy casting recited in  claim 5 , having a thermal conductivity of 160 W/(m·k) or more. 
     
     
         9 . A method for manufacturing aluminum alloy castings having excellent thermal conductivity, comprising undertaking a heating and holding treatment for 1 hour or longer at 400-510 degrees Celsius on an aluminum alloy casting material of a composition described in  claim 5 .