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New insights into ω-embrittlement in high misfit metastable β-titanium alloys: Mechanically-driven ω-mediated amorphization
- Source :
- Materials & Design, Vol 205, Iss, Pp 109724-(2021)
- Publication Year :
- 2021
- Publisher :
- Elsevier BV, 2021.
-
Abstract
- ω-embrittlement is ubiquitous in metastable β-titanium (Ti) alloys, while the fundamental understanding on the damage-fracture mechanism hitherto remains elusive. In this study, we systematically investigate ω-embrittlement of high misfit Ti-10Cr (wt.%) alloys by coupling experiments and first-principles calculation. It is found that brittle cleavage-like fracture prevails in tensile samples, irrespective of the quenching or subsequent aging states. Microscopically, cracks nucleation and propagation proceed along slip bands, inside which ω-lattices are first disordered and then the localized (β + ω)-amorphous-like structures are developed in the shape of white patches. The underlying mechanism of mechanically-driven localized amorphization is that due to the remarkable covalent character of atomic bonding of ω-precipitates caused by composition partitioning of the Cr element, ω-precipitates impart extremely high energy barrier opposed to dislocation gliding and render dislocations pile-up ahead of ω-precipitates, thus leading to their lattice disordering. It is unveiled that the hydrostatic pressure, serving as the driving force for dislocations pile-up, plays a critical role in this unusual cleavage-like fracture of Ti-10Cr alloys caused by mechanically-driven ω-mediated localized amorphization. Accompanied by the transition from the co-operation of deformation twining and ordinary dislocation slip in the quenched Ti-10Cr alloys to the exclusive ordinary dislocation slip in the long-time aged Ti-10Cr samples, it is unexpected that the resulting tensile fracture strength monotonically decreases to a stress level of ~ 100 MPa. These findings provide new insights into the damage and fracture behavior of high misfit β-titanium alloys, such as Ti-Cr alloys.
- Subjects :
- Materials science
Hydrostatic pressure
Nucleation
02 engineering and technology
Slip (materials science)
010402 general chemistry
ω-precipitates
01 natural sciences
Brittleness
Titanium alloys
General Materials Science
Materials of engineering and construction. Mechanics of materials
Quenching
Condensed matter physics
Mechanical Engineering
Lüders band
Slip band
021001 nanoscience & nanotechnology
Amorphization
0104 chemical sciences
Mechanics of Materials
TA401-492
Deformation (engineering)
Dislocation
0210 nano-technology
Subjects
Details
- ISSN :
- 02641275
- Volume :
- 205
- Database :
- OpenAIRE
- Journal :
- Materials & Design
- Accession number :
- edsair.doi.dedup.....bcfbd0135c67395f902fa2a5189dd052