Thermal Expansion Anisotropy of Zr-2.5Nb Pressure Tube Material on Heating to 1100° C

Abstract

The anisotropic thermal expansion (and contraction) properties of Zr-2.5Nb pressure tube material have been investigated up to 1100°C using a high-resolution dilatometer. The thermal expansion measured along two principal axes of the pressure tube (longitudinal and transverse directions) are compared with calculated values from a derived expression with material parameters (e.g., single-crystal thermal coefficients (alpha and ß phase), texture, phase volume fractions, and phase transformation strain. The calculated thermal expansion is shown to capture the thermal expansion and anisotropic characteristics throughout the phase transformation regime (two phase region) and into the high-temperature single ß-phase domain.