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Fabrication of highly heterogeneous precipitate microstructure in an α/β titanium alloy.
- Source :
-
Acta Materialia . Oct2024, Vol. 279, pN.PAG-N.PAG. 1p. - Publication Year :
- 2024
-
Abstract
- To obtain a synergistic combination of high strength and high ductility in titanium alloys, design and creation of heterogenous precipitate microstructure have attracted increasing attention. Herein, using Ti-3Al-5Mo-4.5V (wt.%, an α / β titanium alloy) as a model alloy, we demonstrated that a highly heterogenous α -phase precipitate microstructures with well-controlled length scale of spatial heterogeneity (i.e., micron-sized primary α and nano-scale secondary α precipitates), can be synthesized through activating the ω-assisted α nucleation transformation pathway that operates in metastable β titanium alloy alone. A detailed analysis of transformation pathway for ω phase and the underlying ω-assisted α nucleation mechanisms is carried out using the integrated advanced characterizations, theoretical calculations and simulations based on DFT, and phase-field modeling. Experimental results show unambiguously that the embryonic ω particles (also known as athermal ω) with partially collapsed structure are incapable of refining secondary α (α s). In contrast, the isothermal ω particles with a complete structural collapse play an important role in assisting α s nucleation, resulting in the formation of the ultrafine α s lamellae at nanoscales after two-step aging heat treatments. The contributions from the isothermal ω particles are then quantified using first-principles calculations and phase-field simulations. It is found that, even though the solute partitioning between a growing isothermal ω particle reduces the α s nucleation driving force in the surrounding β matrix, the elastic interaction between the ω particles and the α s nucleus provides more driving force for α s nucleation at specific locations of the ω/β interface. Our work extends the microstructure design strategy based on ω -assisted α nucleation mechanism from metastable β to α / β Ti-alloys, thereby significantly widening the application space of the strategy. [Display omitted] [ABSTRACT FROM AUTHOR]
- Subjects :
- *HEAT treatment
*NUCLEATION
*MICROSTRUCTURE
*ALLOYS
*DUCTILITY
Subjects
Details
- Language :
- English
- ISSN :
- 13596454
- Volume :
- 279
- Database :
- Academic Search Index
- Journal :
- Acta Materialia
- Publication Type :
- Academic Journal
- Accession number :
- 179502947
- Full Text :
- https://doi.org/10.1016/j.actamat.2024.120302