Tensile Strength of REBCO Tape During Deposition of Subsequential Layers

ReBa<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>Cu<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub>O<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7-x</sub> (REBCO) tapes require high yield strength in service; otherwise, excessive stress may seriously damage their superconducting performance or even induce quenching. Therefore, investigating the factors influencing the mechanical performance of REBCO tapes becomes critically important. In this study, the variations in the tensile strength of REBCO tapes during the deposition of various film layers (buffer layer, superconducting layer, Ag layer, and Cu layer) were systematically investigated. The results showed that the yield strength decreased by 525 MPa (approximately 37%) from the bare Hastelloy substrate to the fully fabricated REBCO tape, with the high-temperature deposition of the REBCO layer being the primary contributor to this reduction. Microstructural analysis of each Hastelloy substrate sample, using electron backscatter diffraction (EBSD) revealed that the REBCO layer deposition led to an increase in grain size and a considerable decrease in dislocation density within the Hastelloy substrate. This microstructural transformation directly contributed to the overall decrease in the yield strength of the REBCO tape. Furthermore, the observed changes in the microstructure of the Hastelloy substrate were attributed to the excessively high temperature employed during the coating process. The findings of this study may provide insights for manufacturers seeking to enhance the mechanical performance of their tapes.