Neutron diffraction investigation of phase compositions in as received and modified Zr-2\ub75Nb pressure tube materials

Zr-2\ub75Nb alloy is used for the pressure tubes in CANDU [CANDU\uae (CANada Deuterium Uranium) is a registered trademark of Atomic Energy of Canada Limited.] reactor fuel channels. Three phases (\u3b1, \u3b2 and \u3c9) of zirconium are known to exist in Zr-2\ub75Nb alloy pressure tube materials. An as received pressure tube is composed mainly of a phase and approximately 8% b phase material. In the last step of production, the pressure tube is given a steam autoclave treatment (i.e. thermal aging at 400\ub0C for 24 h). This treatment results in decomposing the b phase into an Nb enriched b phase and a metastable v phase material. In the present experiment, as received pressure tube materials were modified by high temperature annealing and thermal aging treatments. This paper presents a neutron diffraction investigation into the phase compositions in the modified materials at room temperature using the C-2 high resolution neutron powder diffractometer at the Canadian Neutron Beam Centre. \ua9 2015 Canadian Institute of Mining, Metallurgy and Petroleum Published by Maney on behalf of the Institute.Peer reviewed: YesNRC publication: Ye