Structural and magnetic properties of V-Ti-Si alloy superconductors

The structural and magnetic properties of the as-cast and annealed V0.6-xSixTi0.4 (x = 0, 0.05, 0.10, 0.15) alloy superconductors are reported here. It is found that addition of silicon to the V-Ti alloys results in eutectic precipitation of Ti5Si3-phase in the body centred cubic (bcc) \b{eta}-V-Ti matrix. In the as-cast V0.6-xSixTi0.4 alloys, the superconducting transition temperature (TC) changes non-monotonically with increasing silicon content whereas after annealing, it is about 7.7 K for all the alloys. On the other hand, the upper critical field decreases and the coherence length increases after annealing in the x = 0.10 alloy. The variations in the superconducting properties in the alloys are related to the solubility of 6 at.% Si in the V0.60Ti0.40 alloy and the vanadium enrichment in the \b{eta} matrix due to the precipitation of Ti5Si3 phase.