Towards a sustainable fabrication of cryomagnets: Melting‐driving approaches for recycling failed REBa ₂ Cu ₃ O _x bulks

Abstract Recycling failed REBa ₂ Cu ₃ O _x (RE123 or REBCO, RE: rare earth elements) bulks is a matter of significant importance in the manufacture of superconducting cryomagnets for practical applications. However, bulks with high solid fraction and high T _p (peritectic temperature) are difficult to recycle. In order to solve this problem, we first gave a comprehensive classification of failed bulks based on their macrostructures, determined by the volume ratio between poly‐crystalline grains (PCG) and solidified liquid phase (SLP) of the bulks, which is positively correlated with the difficulty level of melting the bulks. Furthermore, particularly for hard‐to‐melt samples, we developed a novel melting‐driving recycling process, in which an additional step, high‐temperature remelting plus quenching, was employed before a normal regrowing step. As a result, we succeeded in recycling the failed SmBCO bulks featuring high T _p and structures of fully‐grown PCG, which demonstrated comparable superconducting performance to ones prepared by normal top‐seeded melt‐growth. This study opens a new direction of recycling all kinds of failed RE123 bulks and other ceramic materials, making their industrial applications more sustainable and economic.