Tensile strengths and Young’s modulus of thin copper and copper-nickel (CuNi44) substrates

摘要

In this paper we report a method to determine tensile strengths and Young's modulus of cubic biaxial textured metal tapes used as substrate materials for coated conductors (CC). Simplicity, rapidity and reproducibility of the procedure are important for the evaluation of continuous in-house productions. Our approach is based on the EN 10002-1 B tensile test method. A key role for satisfactory results is the sample preparation of 100 - 250 μm thick tapes, which will be described in detail. Copper (E-Cu57) can be successfully transformed to cubic biaxial textured substrates. Best results were achieved by annealing between 750℃ and 850℃ in reducing atmosphere. Best FWHM values for the ψ scan are 5.51° and for the φ scan are 4.5°. Pole figure analysis verified the sharp {001} <100> texture of the tape. Vickers hardness measurements (HV 0.1) for the cold worked material yielded values of 135 and for the annealed tape, values of 37. The ultimate tensile yield strength Rm of the textured substrate is 150 MPa and thus significantly lower than that for the cold worked material (413 MPa). Cubic biaxial substrates could be manufactured from Isotan CuNi44 (WM49) bars. Best results were achieved by annealing at 1200℃ in reducing atmosphere. Pole figure analysis verified the {001} <100> texture with other low intensity texture components. Vickers hardness measurements (HV 0.1) for the cold worked material yielded values of 236 and for the annealed tape values of 92. The ultimate tensile yield strength R_m of the textured substrate is 300 MPa and thus significantly lower than that for the cold worked material (723 MPa).