Microstructural evolution and properties of a Ti-Nb-Ta-Zr-O prepared by high-pressure torsion
•TNTZO alloy was processed by high-pressure torsion under different conditions.•The samples' phase volume fraction were investigated by Rietveld refinement.•β-phase stability increases relative to α"-phase after severe plastic deformation.•α" → β reverse martensitic transformation was...
Gespeichert in:
Veröffentlicht in: | Journal of alloys and compounds 2021-05, Vol.864, p.158828, Article 158828 |
---|---|
Hauptverfasser: | , , , , , , |
Format: | Artikel |
Sprache: | eng |
Schlagworte: | |
Online-Zugang: | Volltext |
Tags: |
Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
|
Zusammenfassung: | •TNTZO alloy was processed by high-pressure torsion under different conditions.•The samples' phase volume fraction were investigated by Rietveld refinement.•β-phase stability increases relative to α"-phase after severe plastic deformation.•α" → β reverse martensitic transformation was clearly observed.•Significant hardening and grain refinement were obtained after HPT.
[Display omitted]
In this work, the Ti-29Nb-13Ta-4.6Zr-0.07O (TNTZO) alloy was processed by high-pressure torsion (HPT), and its microstructure, phase stability, elastic behavior, mechanical properties and deformation mechanisms were determined for samples prepared under different conditions. An increase in β-phase stability relative to martensite and a significant hardening was observed after severe plastic deformation. The increase in β-phase stability is attributed to the sharp increase in the system’s Gibbs free energy that occurs when the α"-laths reach a critical nanometer-size during the HPT processing. This system’s Gibbs free energy increase triggers the occurrence of the α"→ β reverse martensitic transformation. The greater hardness can be related to three factors: microstructural refinement; high dislocation density and stress-induced formation of the ω-phase. Plastic deformation is based on conventional slip, detwinning, stress-induced martensite formation, as well as the reverse martensitic transformation. The reverse martensitic transformation observed during HPT corresponds to a recently discovered mechanism that has not been well addressed in the literature until now. In this paper, this new mechanism is clearly detected and detailed discussed based on a systematic Rietveld refinement, in-depth microscopy, and calorimetry. |
---|---|
ISSN: | 0925-8388 1873-4669 |
DOI: | 10.1016/j.jallcom.2021.158828 |