ALUMINUM ALLOY CASTING HAVING SUPERIOR HIGH-TEMPERATURE STRENGTH AND THERMAL CONDUCTIVITY, METHOD FOR MANUFACTURING SAME, AND ALUMINUM ALLOY CASTING PISTON FOR INTERNAL COMBUSTION ENGINE

摘要

An aluminum alloy casting excellent in high temperature strength and thermal conductivity, a method of producing the same, and an aluminum alloy piston for internal combustion engine using this casting. An aluminum alloy casting having a chemical composition comprisingSi: 12.0 to 13.5 mass %Cu: 4.5 to 5.5 mass %Mg: 0.6 to 1.0 mass %Ni: 0.7 to 1.3 mass %Fe: 1.15 to 1.25 mass %Ti: 0.10 to 0.2 mass %P: 0.004 to 0.02 mass % anda balance of Al and unavoidable impurities, whereinin an observed field of view of 0.2 mm², the major axis length of the Al—Fe—Si based crystallites is 100 μm or less by average length of 10 crystallites from the largest down. The method for producing the casting comprising casting a melt of aluminum alloy having the above chemical composition at cooling rate of 100° C./sec or more, then performing aging treatment.