Abstract: 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 comprising Si: 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 % and a balance of Al and unavoidable impurities, wherein in an observed field of view of 0.2 mm2, the major axis length of the Al—Fe—Si based crystallites is 100 ?m 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.

Abstract: 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 comprising Si: 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 % and a balance of Al and unavoidable impurities, wherein in an observed field of view of 0.2 mm2, the major axis length of the Al—Fe—Si based crystallites is 100 ?m 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.

Abstract: A piston for internal combustion engine has both fatigue strength and wear resistance without increased production cost. At least one of a combustion chamber surface, a skirt rib, a pin boss rib which connects a pin boss and a crown, a lower portion of the pin boss casting surface, and a surface layer including the casting surface is a first eutectic structure in which primary crystal Si does not crystallize. A top ring groove and a pin holing of a piston pin are finished surfaces obtained by eliminating the surface layer by means of machining. The layer including the finished surface is a second eutectic structure in which the primary crystal Si crystallizes.

Abstract: A piston for internal combustion engine has both fatigue strength and wear resistance without increased production cost. At least one of a combustion chamber surface, a skirt rib, a pin boss rib which connects a pin boss and a crown, a lower portion of the pin boss casting surface, and a surface layer including the casting surface is a first eutectic structure in which primary crystal Si does not crystallize. A top ring groove and a pin holing of a piston pin are finished surfaces obtained by eliminating the surface layer by means of machining. The layer including the finished surface is a second eutectic structure in which the primary crystal Si crystallizes.