Aging Effects in REBCO Tapes Solder Joint Made With Indium-Tin

초록

With the promises of nuclear fusion, an increasing number of fusion magnet projects are employing (RE)Ba2Cu3O7-delta (REBCO) tapes. These magnets often include multiple demountable joints, which typically incorporate low-temperature solder either in the joint itself or in the cable. Such solders usually contain elements that diffuse readily in copper, raising concerns about the aging effects. This study investigates the impact of the InterMetallic-Compound (IMC) growth on the joints properties through room-temperature aging and annealing. Eutectic indium-tin solder joints stored for nine months in a desiccator did not exhibit any significant change in their properties. Given the strong temperature dependence of the IMC growth, annealing at 100 degrees C was performed to simulate long-term effects. After 6 to 8 days of annealing, critical current degradation was measured in all samples containing solder, indicating that the IMC had grown to the REBCO layer deteriorating it. Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) analyses revealed that even after 20 days, solder elements reached the REBCO layer only in regions where the solder was abundant.

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