Studies on the formation of V₃Ga and V₃Si superconducting compounds by a new diffusion process

Abstract

In the present work, diffusion between vanadium and Cu-20 at.% Ga alloy and that between vanadium and Cu-20 at.% Si alloy were studied. An intermetallic compound, V₃Ga, is formed easily by the selective diffusion of gallium from the Cu-Ga alloy to the vanadium. V₅Si₃ and V₃Si are formed also by the selective diffusion of silicon from the Cu-Si alloy to the vanadium. Copper scarcely dissolves either in V₃Ga, V₅Si₃ or V₃Si. Copper is not effective for enhancing the formation of V₃Si unlike the case of V₃Ga. A large super-conducting critical current density, J _c, is obtained in the V₃Ga formed at temperatures below 700° C while a much smaller J _c is obtained in the V₃Si formed at 800° C. Changes in J _c due to the heat-treatment can be interpreted by the grain growth of the compounds.