The phase transformations in an as-received Zr-2.5Nb pressure tube material were characterized in detail by neutron diffraction. The texture and volume fraction of α and β phases were measured on heating at eight different temperatures 373 K to 1323 K (100°C to 1050°C) traversing across the α/(α + β) and (α + β)/β solvus lines, and also upon cooling at 1173 K and 823 K (900°C and 550°C). The results indicate that the α-phase texture is quite stable, with little change in the {0002} and {112̄0} pole figures during heating to 1123 K (850°C). The β-phase volume fraction increased while a slight change in texture was observed until heating reached 973 K (700°C). On further heating to 1173 K (900°C), there appears a previously unobserved α-phase texture component due to coarsening of the prior primary α grains; meanwhile the transformed β-phase texture evolved markedly. At 1323 K (1050°C), the α phase disappeared with only 100 pct β phase remaining but with a different texture than that observed at lower temperatures. On cooling from the full β-phase regime, a different cooldown transformed α-phase texture was observed, with no resemblance of the original texture observed at 373 K (100°C). The transformed α-phase texture shows that the {0002} plane normals are within the radial-longitudinal plane of the pressure tube following the Burgers orientation relationship of (110) bcc//(0002) hcp and [1̄11] bcc//[112̄0] hcp with a memory of the precursor texture of the primary α grains observed on heating at 1173 K (900°C).

Additional Metadata
Persistent URL dx.doi.org/10.1007/s11661-011-0914-6
Journal Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
Citation
Fong, R.W.L., Miller, R., Saari, H, & Vogel, S.C. (2012). Crystallographic texture and volume fraction of α and β phases in Zr-2.5Nb pressure tube material during heating and cooling. Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science, 43(3), 806–821. doi:10.1007/s11661-011-0914-6