Abstract: The present invention relates to a high-strength copper alloy forging material having properties of high hardness, high strength and high thermal conductivity. The high-strength copper alloy forging material contains, in mass %, 3 to 7.2% of Ni, 0.7 to 1.8% of Si, 0.02 to 0.35% of Zr and 0.002 to 0.05% of P, and further contains 1.5% or less of one or two or more of Cr, Mn and Zn in total, as needed, whereby appropriate amounts of Zr and P act to cause cracks to be less likely to occur in the material during working or heat treatment. After the working and the heat treatment, the forging material of the invention can have properties of high hardness, high strength and high thermal conductivity, and can be suitably used for resin injection mold materials, aircraft components and the like.

Abstract: An object of the invention is to make it possible to produce a copper alloy in which the S content is reduced with no contamination with Al, which has a good casting surface and good internal properties and in which eutectic compounds are refined. The invention relates to a slag for electroslag remelting for copper alloy, including CaF2: 20 to 45% by mass, CaO: 10 to 30% by mass, SiO2: 10 to 30% by mass, LiF: 10 to 20% by mass, and ZrO2: 5 to 15% by mass with other impurities: at most 1% by mass, and satisfying a formula: 17.0(LiF content+ZrO2 content)?556?CaF2 content?4.1(LiF content+ZrO2 content)?80.9, and the invention relates to a method for producing a copper alloy with the slag.

Abstract: An object of the invention is to make it possible to produce a copper alloy in which the S content is reduced with no contamination with Al, which has a good casting surface and good internal properties and in which eutectic compounds are refined. The invention relates to a slag for electroslag remelting for copper alloy, including CaF2: 20 to 45% by mass, CaO: 10 to 30% by mass, SiO2: 10 to 30% by mass, LiF: 10 to 20% by mass, and ZrO2: 5 to 15% by mass with other impurities: at most 1% by mass, and satisfying a formula: 17.0 (LiF content+ZrO2 content)?556?CaF2 content?4.1 (LiF content+ZrO2 content)?80.9, and the invention relates to a method for producing a copper alloy with the slag.