Phase transformations in a heterogeneous Ti-xNb-7Zr-0.8O alloy prepared by a field-assisted sintering technique

0555692 - ÚFP 2022 RIV GB eng J - Journal Article
Kozlík, J. - Preisler, D. - Stráský, J. - Veselý, J. - Veverková, A. - Chráska, Tomáš - Janeček, M.
Phase transformations in a heterogeneous Ti-xNb-7Zr-0.8O alloy prepared by a field-assisted sintering technique.
Materials and Design. Roč. 198, January (2021), č. článku 109308. ISSN 0264-1275. E-ISSN 1873-4197
R&D Projects: GA ČR(CZ) GA19-11275S
Institutional support: RVO:61389021
Keywords : Field assisted sintering technique (FAST) * Gibbs free energy * Heterogeneity * Phase transitions * Titanium alloys
OECD category: Materials engineering
Impact factor: 9.417, year: 2021
Method of publishing: Open access
https://www.sciencedirect.com/science/article/pii/S0264127520308443?via%3Dihub

Biomedical metastable alloy Ti-xNb-7Zr-0.8O with a compositional gradient of Nb was prepared from elemental powders by a field-assisted sintering technique (FAST). The aim was to investigate phase transformations over a wide range of compositions, facilitating the designing of biomedical Ti alloys. Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) investigations revealed that Nb-rich regions retained the β phase, surrounded by transition region consisting of the β and ω phases, while Nb-lean regions consisted of the α and β phases. The Nb concentration, above which formation of the ω phase occurs during cooling instead of the α phase, was determined to be 22 wt%, an important parameter for the low-modulus alloy design. The paper validates the viability of using FAST to prepare heterogeneous Ti alloys permitting to study microstructure over a wide range of compositions. This technique could also be readily used as a high-throughput method for designing other alloy systems. The experimental results were supplemented by calculation of Gibbs energy curves and schematic phase diagrams, which allowed to explain a competition between α and ω formation depending on alloy composition. Such semi-empirical approach can serve as a useful tool for general alloy design, in particular for biomedical Ti alloys.
Permanent Link: http://hdl.handle.net/11104/0330156