Development of large area and high-strength CuAg alloy plates for high-field Bitter coils

A poly Bitter coil is desired as the resistive coil of a hybrid magnet from the viewpoint of easy fabrication. Recently, high silver content and high-strength CuAg alloy is developed. This alloy, however, is so hard. It is difficult to make thin and very flat plates of the CuAg alloy with large area. We succeeded in fabricating 26 mass%Ag-Cu plates with the thickness of 0.8 mm and an area of 340 mm×340 mm square by using a special rolling process and heat treatment. The plates have a maximum 0.2% proof stress greater than 670 MPa and a mean electrical conductivity greater than 78%IACS at room temperature. The magnetoresistance of CuAg alloys were measured up to 15 T magnetic fields. The increase in the resisitivity was very small.