Abstract
We present here the studies on the effect of annealing on the structural and magnetic properties of V1−xZrx (x = 0.33 and 0.40) superconducting alloys. We show that the γ-ZrV2 phase grows at the expense of (α-Zr)-(γ-ZrV2) eutectic microstructure when V1−xZrx alloys are annealed at 1473 K for one week. The annealed samples predominantly have a γ-ZrV2 phase with small amounts of β-V and α-Zr phases. The irreversibility field, critical current density, and pinning force density of the as-cast samples are found to be significantly higher than those of annealed alloys. These results indicate that eutectic microstructure is important in utilizing these materials for high field applications.
Highlights
C15 Laves phase ZrV2 and HfV2 based systems have been considered promising materials for superconducting applications in neutron radiation environments.1,2 These materials are soft3 and brittle at room temperature and below.4 the development of the powder in tube (PIT) technique, rapid heating and quenching (RHQ), and rod restack process, for fabrication of superconducting wires, draws new research interest in these materials.5,6 Recently, we have shown that as-cast V1−xZrx (x = 0.05–0.40) alloys contain five different structural phases.7,8 Figure 1 shows the (a) equilibrium and (b) non-equilibrium phase diagrams of V1−xZrx alloys
The non equilibrium phase diagram, which corresponds to arc melted as-cast V1−xZrx alloys, is constructed from the results of our previous study
We have shown that the critical current density (JC) of the V1−xZrx alloys with x > 0.29 is in the range of modern Nb–Ti wires7 due to the grain boundaries generated by the eutectic type reaction and the point defects such as β-precipitates which, respectively, pin the flux lines in the low and high magnetic fields
Summary
We have shown that the critical current density (JC) of the V1−xZrx alloys with x > 0.29 is in the range of modern Nb–Ti wires7 due to the grain boundaries generated by the eutectic type reaction and the point defects such as β-precipitates which, respectively, pin the flux lines in the low and high magnetic fields. The ρ(T) of the annealed samples in the range from the superconducting transition temperature (TC) to 300 K is larger than that of the corresponding as-cast alloys.
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