Development of A-15 (V3Ga) superconducting material through controlled precipitation

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Abstract
A monolithic process has been used to produce superconducting materials by controlled precipitation of the A‐15 (V3Ga) phase inside the bcc matrix of a V‐rich solid solution. Ingots of V‐(17∼19 at.%)Ga were prepared by arc melting, homogenization, and quenching, were deformed at intermediate temperature into tape, and were aged at temperatures in the range 600–1000 °C to precipitate the A‐15 phase. The maximum critical transition temperature (∼14.8 °K) was found in materials aged at temperatures of 750 °C or below. At these aging temperatures the Tc initially increases with aging time, and passes through a distinct maximum. The source of the exceptionally high Tc is not clear, but may be attributable to a combination of high solute content and internal strain in the small A‐15 precipitate particles.