Pinning mechanism in a continuous ultrafine Nb₃Al multifilamentary superconductor

For Nb₃Al multifilamentary superconductors fabricated by a newly developed composite process using continuous ultrafine Al-based alloy cores and pure Nb matrix, J_c properties have been investigated in detail in regard to the size and morphology of the Al core. A significant enhancement in pinning force caused by reducing the Al core size and an anisotropy in J _c observed in a rolled tape have indicated that the Nb ₃Al-matrix (or core) interface acts as a dominant pinning center of fluxoids.