Intermediate phases in V-Re system

Methods of X-ray analysis, optical microscopy, determination of phase microhardness, superconducting transition temperature have been used to investigate the phase composition and transition phases of cast and annealed vanadium-rhenium alloys, containing 69-86 at.% of rhenium. The σ-phase in the alloy, containing 76 at.% Re is identified. The lattice periods are a=0.944+-0.001 nm, c=0.489+-0.001 nm, sp. group Dsub(4hsup(14)), structural type D8sub(b). The lower temperature boundary of existence of σ phase is between 1723 and 1773 K. A-phase is found in the alloy close to 71 at.% Re, its structural type A-15 (Cr3Si), sp. group Pm3n, lattice period a=0.48783+-0.00007 nm. The A-phase appears according to the peritectoid reaction α+σ reversible A at the temperature between 2223 and 2473 K and undergoes eutectic decomposition at 1373 K