Recent Progress in Application of Internal Oxidation Technique in Nb3Sn Strands

The internal oxidation technique can generate ZrO ₂ nano particles in Nb ₃ Sn strands, which markedly refine the Nb ₃ Sn grain size and boost the high-field critical current density (J _c ). This paper summarizes recent efforts on implementing this technique in practical Nb ₃ Sn wires and adding Ti as a dopant. It is demonstrated that this technique can be readily incorporated into the present Nb ₃ Sn conductor manufacturing technology. Powderin-tube (PIT) strands with fine subelements (~25 μm) based on this technique were successfully fabricated, and proper heat treatments for oxygen transfer were explored. Future work for producing strands ready for applications is proposed.