The formation mechanism of the higher performanceV₃Ga phase on the high Ga content Cu-Ga compound/V diffusion reaction through the high-temperature XRD analysis

V₃Ga compound has a shorter radioactive decay time compared with Nb-based compounds and it will be one of the candidate superconducting magnet materials for advanced low activation fusion reactor systems. !Recently, we succeeded in developing new V₃Ga wires, fabricated via the PIT process using high Ga content Cu-Ga compounds above Cu-Ga solid solution composition. Jc and H_c2enhancements of V₃Ga wire due to increasing three times of the V₃Ga volume fraction were also confirmed. For the further microstructure control, in-situ observation of diffusion reaction with increase of temperature using High-Temperature X-ray diffraction (HT-XRD) was measured. Various high Ga content Cu-Ga compounds were composed with Cu₃Ga (β phase: 30at%Ga), Cu₉Ga₄(γphase: 40at%Ga) and CuGa2 (δ phase: 64at%Ga) compounds. Especially, CuGa₂ compound has much lower melting point (254 °C) compared with various Cu-Ga compounds. In the case of diffusion reaction including CuGa₂ phase, V₃Ga phase was formed by the second step diffusion reactions; the first one is solid-liquid diffusion between the dissociated Ga liquid phase and metal V, the second one is soild-solid diffusion reaction between solid phase formed by the first step reaction and metal V.