STRUCTURAL-PROPERTIES AND STABILITY OF THE BCC-PHASES AND OMEGA-PHASES IN THE ZR-NB SYSTEM .1. NEUTRON-DIFFRACTION STUDY OF A QUENCHED AND AGED ZR-10-WT-PERCENT NB ALLOY

This paper deals with the composition dependence of the lattice parame ters and other structural and stability properties of the bcc and omeg a phases in the Zr-Nb system. Our approach combines a neutron diffract ion measurement on a Zr-10 wt% Nb alloy with the assessment of previou sly published experimental data. Measurements are reported for the all oy in both the as-quenched condition and after an aging treatment at 6 73 K. The composition changes in bcc and omega occurring during the ag ing are examined. In addition, a critical analysis is presented of the existing estimation method for composition which makes use of informa tion about the lattice parameters. The new experimental data obtained in this work are also used in comparisons with previous studies of bcc and omega based on X-ray diffraction methods. The existence of some s ignificant discrepancies on the structural parameters of the omega pha se is discussed.