Titanium-Zirconium-Niobium Ternary Alloys

Abstract

The development of Ti-Zr-Nb alloy superconductors in the early 1960’s was motivated by a desire to combine the advantages of Zr-Nb and Ti-Nb alloys and at the same time to avoid their disadvantages. In so doing, the following electrical properties were taken into consideration: (a) the maximum transition temperature in the Zr-Nb system of 10.9 K at about 80 at.% Nb, as compared to the 9.7 K of the Ti-Nb system, at 60–70 at.% Nb; (b) the maximum 4.2-K upper critical field in the Zr-Nb system of 95 k0e, considerably less than the 113 k0e of Ti-Nb. On the mechanical-property side, recognizing that Zr-Nb₅₀, for example, underwent a ductile-brittle transition at about 100°C [Doi68^b], it was deemed advantageous to substitute some Ti for Zr in order to lower the transition point, which then dropped to room temperature with 1 at.% Ti and to about -50°C with 10 at.% Ti.