DEVELOPMENT OF A HIGH-STRENGTH, HIGH CONDUCTIVITY COPPER-SILVER ALLOY FOR PULSED MAGNETS

Development of highly conductive materials with high strength is requisite for conductors of high-field magnets. To develop such materials, the Cu-Ag alloys (2-60 at%) and their fabrication methods have been investigated. The Cu-Ag alloys were prepared by melting electrolytic Cu and pure Ag pellets in an argon atmosphere, and then cold-drawn to a 99.2% reduction in area. The heat treatments were performed several times during the drawing process. Strength and conductivity of the Cu-Ag alloys vary with thermomechanical treatments. The optimum combination of high strength and high electrical conductivity were obtained by cold-drawing the alloy with intermediate heat treatments at 350-450-degrees-C for 1-2h. The intermediate-heat-treated Cu-16 at%Ag composite with 99% reduction in area had an ultimate tensile strength of 1000 MPa and an electrical conductivity of 80 IACS% at room temperature. Since the Cu-Ag alloys fabricated by the present method have higher values of both tensile strength and conductivity than those of Cu-Nb and other Cu-based alloys, they would be one of the most promising conductor materials for the high field magnets.