EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Ti-xNb-7Zr-0.8O alloy was prepared from elemental powders by a field-assisted sintering technique (FAST). Nb is the main beta-stabilizing element, as well as being the element with the slowest diffusion. A compositional gradient of Nb was produced in the alloy, allowing the observation of phase transformations over a wide range of compositions. Scanning and transmission electron microscopy investigations revealed that Nb-rich regions retained the metastable β phase, surrounded by transition region consisting of the β and ω phases and Nb-lean regions consisting of the α and β phases. The critical concentration of Nb determining whether α or ω will precipitate during cooling was determined to be 22 wt%. The observed as-sintered microstructure is discussed with respect to the Gibbs free energy curves and the phase diagram.The paper validates the viability of using FAST to prepare heterogeneous alloys permitting the study of phase transformations over a wide range of compositions.