Improvement of Strain Tolerance in RE-123 Coated Conductors by Controlling the Yielding Behavior of Hastelloy C-276 Substrates

Mechanical properties of Hastelloy C-276 substrate with different pre-treatment were investigated. Discontinuous yielding was observed in the solution treated substrate after annealing at the maximum process temperature of IBAD and ISD. In the smooth rolled substrates, yield strength higher than 1 GPa can be attained and even after annealing continuous yielding can be maintained. Annealing enlarges elastic limit by pinning of the mobile dislocations. Microstructure observation using transmission electron microscopy shows that two kinds of candidates for the pinning site of the dislocations exist such as precipitates and short range ordering region in the discontinuous yielding substrate. Improvement of strain at quenching was confirmed by utilizing continuous yielding substrate with higher elastic limit.