Transformation Heat Treatment of Rapidly Quenched Nb3Al Precursor Monitored In Situ by High Energy Synchrotron Diffraction

Nb3Al superconductors are studied for use in high field magnets. Fine-grained Nb3Al with nearly stoichiometric Al content is obtained by a rapid heating quenching and transformation process. We describe a nondestructive in situ study of the transformation process step of a rapid heating quenching Nb3Al precursor wire with ramp rates of either 120 degrees C/h or 800 degrees C/h. High-energy synchrotron X-ray diffraction measurements show the transformation from a Nb(Al)(SS) supersaturated solid solution into Nb3Al. When heating with a ramp rate of 120 degrees C/h, a strong reduction of the Nb(Al)(SS) (110) diffraction peak component is observed when the temperature exceeds 660 degrees C. Additional diffraction peaks are detectable in the approximate temperature interval 610 degrees C-750 degrees C and significant Nb3Al growth is observed above 730 degrees C.