Textural and microstructural evolutions during deformation and annealing of Nb–1% Zr–0.1% C (wt%) alloy

Abstract

Evolution of texture and microstructure in the Nb–1% Zr–0.1% C (wt%) alloy has been studied as a function of deformation and annealing treatments. The Nb alloy was deformed by rolling at room temperature up to 40%, 60% and 80% thickness reduction. Samples reduced to 60% thickness were annealed at 1300°C for different soaking periods (0, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6 and 7h). All the samples were characterised using X-ray diffraction (XRD), electron back scattered diffraction (EBSD) and analytical transmission electron microscopy (ATEM). Texture results have shown that deformed and annealed samples exhibited the development of typical bcc texture i.e., α and γ-fibre texture. With increasing percentage of deformation (>40%), γ-fibre becomes the dominant texture. Samples deformed up to 80% have predominantly {111}〈110〉 texture. Rolling textures were simulated using Taylor models. The pancake relaxed constraint Taylor model, consideration of {110}〈111〉 type of slip systems exhibited good agreement with experimentally observed rolling texture. In the case of annealed samples, with increasing soaking time, volume fraction of α-fibre remained constant and the γ-fibre volume fraction decreased up to 0.5h soaking time, followed by it being constant. Samples annealed at 1300°C for 7h showed {100}〈110〉 orientation texture. ATEM results showed that with increasing annealing time at 1300°C, Nb/Zr ratio in the carbide precipitates decreases.