Tantalum-Niobium Alloy Diffusion Barriers for Superconducting Nb3Sn Wires in Fusion Applications
Fusion magnets using cable in conduit conductors require Nb3Sn wires having high residual resistivity ratio (RRR) to ensure adequate stability. The diffusion barrier in Nb3Sn composite wire is one of the key factors controlling the RRR of the wire. Ta40wt.% Nb diffusion barriers have been investigated for application to fusion type wires. Ta40wt.% Nb diffusion barriers exhibit excellent fabricability in the wire drawing process and yield residual resistivity ratio values in excess of 300 (bare wire surface) and L50 (Cr plated wire surface). The hysteresis loss due to the A15 formed as a layer on the Ta40wt.% Nb diffusion barrier is minimal. Comparisons of Ta40wt.% Nb diffusion barriers to barriers made of V, Nb and Ta are also performed.
KeywordsDiffusion Barrier Hysteresis Loss Composite Wire Minimum Average Maximum Wire Drawing Process
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