Abstract
The influence of rapid quenching and hydrogenation on the structure and phase composition of niobium-rich NbAl alloys was investigated. Starting ingots were prepared by conventional arc melting of compacted powder mixtures. The phase diagram for NbAl, presented by Jorda et al., was confirmed in the examined concentration range up to about 30 at.% aluminium. Specimens were quenched with cooling rates not less than 104 K s−1, both from the solid and liquid state. A metastable extension of the niobium solid solution up to 27 at.% aluminium was obtained after quenching small droplets from temperatures T ⩾ 2200 °C. Contrary to previous publications, it is shown that rapid quenching of solids (19–24 at.% aluminium) from 1750 °C in a eutectic GaIn bath does not lead to the formation of metastable states in the region of the Nb3Al phase. Ductile Nb-Al powders of an average composition “Nb3Al” were prepared with a combined hydridingdehydriding process. The retransformation of the metastable powders was determined to occur in the temperature range between 710 and 860 °C depending on the aluminium concentration. Based on these findings, a new perspective results for the powder metallurgical fabrication of Nb3Al superconductors.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
