Effect of the fabrication route on the phase and volume changes during the reaction heat treatment of Nb₃Sn superconducting wires

Summary

This experimental study combines multiple advanced characterisation techniques to map phase and volume changes occurring during reaction heat treatment of Nb₃Sn superconducting wires used in high-field accelerator magnets. The work reveals that whilst phase evolution below 450 °C is similar across three wire fabrication routes (RRP, PIT, IT), distinct differences emerge at higher temperatures, with the strongest volume increase (≈5%) observed in RRP wire above 600 °C. These findings are directly relevant to optimising fabrication routes and predicting coil dimensional changes in accelerator magnet production.

UK applicability

This research is likely of relevance to UK particle accelerator facilities and superconductor manufacturers, particularly those involved in large-scale magnet development for research infrastructure. The findings could inform process optimisation at UK-based superconductor production and research institutions.

Key measures

Phase evolution (Cu₆Sn₅ formation and peritectic transformation), wire diameter changes, volume changes during reaction heat treatment, temperature-dependent microstructure evolution

Outcomes reported

The study characterised phase and microstructure changes during reaction heat treatment of three types of Nb₃Sn superconducting wires (RRP, PIT, IT) using in situ differential scanning calorimetry, synchrotron X-ray diffraction, and micro-tomography. Wire diameter changes and volume evolution were measured in situ by dilatometry and correlated with phase formation.

Topic tags