Tuning the strength and ductility balance of a TRIP titanium alloy

Ellyson, Benjamin; Klemm-Toole, Jonah; Clarke, Kester D.; Field, Robert D.; Kaufman, Michael J.; Clarke, Amy J.

doi:10.1016/j.scriptamat.2020.113641

Cited by 44 publications

(16 citation statements)

References 27 publications

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“…Finally, the elastic part of the loading curve remains almost linear, without doubleyielding as sometimes reported, see e.g. [3,23]. All these mechanical evidences strongly suggest that the stress-induced martensitic transformation cannot be considered as a major deformation mechanism in this alloy.…”

Section: Mechanical Propertiessupporting

confidence: 80%

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Accommodation mechanisms in strain-transformable titanium alloys

Danard

Martin

Lilensten

et al. 2021

Materials Science and Engineering: A

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Section: Mechanical Propertiessupporting

confidence: 80%

“…Therefore, the yield strength remains rather high, compared to that of TRIP/TWIP alloys with TRIP as a primary deformation mechanism, and where the formation of martensite occurs at low stress, leading to rather low yield strengths [1,3,10,23,41].…”

Section: Figure 7: A) Ebsd-ipf Images Along the Rolling Direction Of ...mentioning

confidence: 99%

Accommodation mechanisms in strain-transformable titanium alloys

Danard

Martin

Lilensten

et al. 2021

Materials Science and Engineering: A

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“… These results suggest that the negative effect of ω-phase on ductility can be remedied by following a careful heat treatment procedure, which promotes the precipitation of ω-phase with higher concentration of β-stabilizers and decreases the elastic constant of this phase. Such heat treatments could be similar to what was reported previously 14 , 52 . Therefore, the ω-phase may not always be detrimental like previously believed.…”

Section: Discussionsupporting

confidence: 89%

First principles computation of composition dependent elastic constants of omega in titanium alloys: implications on mechanical behavior

Salloom

Mantri

Banerjee

et al. 2021

Sci Rep

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For decades the poor mechanical properties of Ti alloys were attributed to the intrinsic brittleness of the hexagonal ω-phase that has fewer than 5-independent slip systems. We contradict this conventional wisdom by coupling first-principles and cluster expansion calculations with experiments. We show that the elastic properties of the ω-phase can be systematically varied as a function of its composition to enhance both the ductility and strength of the Ti-alloy. Studies with five prototypical β-stabilizer solutes (Nb, Ta, V, Mo, and W) show that increasing β-stabilizer concentration destabilizes the ω-phase, in agreement with experiments. The Young’s modulus of ω-phase also decreased at larger concentration of β-stabilizers. Within the region of ω-phase stability, addition of Nb, Ta, and V (Group-V elements) decreased Young’s modulus more steeply compared to Mo and W (Group-VI elements) additions. The higher values of Young’s modulus of Ti–W and Ti–Mo binaries is related to the stronger stabilization of ω-phase due to the higher number of valence electrons. Density of states (DOS) calculations also revealed a stronger covalent bonding in the ω-phase compared to a metallic bonding in β-phase, and indicate that alloying is a promising route to enhance the ω-phase’s ductility. Overall, the mechanical properties of ω-phase predicted by our calculations agree well with the available experiments. Importantly, our study reveals that ω precipitates are not intrinsically embrittling and detrimental, and that we can create Ti-alloys with both good ductility and strength by tailoring ω precipitates' composition instead of completely eliminating them.

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“…CR50A400 and CR75A400 broke after slightly exceeding the yield point during the three-point bending test. It was attributed to the excessive volume fractions of the ω iso phase in the alloys that deteriorated the deformability of the alloy [57]. On the other hand, the bending deflections of CR50A250, CR75A250, CR90A250, and CR90A400 with lower volume fractions of ω iso phase were even greater than 6 mm, while CR75A250 and CR90A250 did not break during the bending test (exceeding the preset bending deflection of 8 mm).…”

Section: Mechanical Propertiesmentioning

confidence: 99%

Effect of thermomechanical treatment on structure and properties of metastable Ti-25Nb-8Sn alloy

Hsu¹,

Wong²,

Chen³

et al. 2021

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In this work, different thermomechanical treatment conditions were used to improve the mechanical performances of Ti-25Nb-8Sn. During cold rolling treatment (50, 75, and 90 %), as-cast Ti-25Nb-8Sn underwent a stress-induced phase transformation from a single β phase to a three-phase structure of α + β + ωstr. After the subsequent aging treatment, Ti-25Nb--8Sn presents three-phase β + α + ωiso (at 250 and 400 • C, for 30 min) and two-phase β + α (at 600 • C, for 30 min). At lower aging temperatures (250 and 400 • C), yield strength/modulus (× 1000) ratios of Ti-25Nb-8Sn are dramatically improved with a maximum increase of 143 %, from 9.06 (as-cast) to 16.2-22.0. Under various thermomechanical treatment conditions in this study, the results show that Ti-25Nb-8Sn has excellent yield strength/modulus (× 1000) ratio (∼ 22) and corrosion resistance after 90 % cold rolling and subsequent aging treatment at 250 and 400 • C for 30 min. K e y w o r d s : titanium alloys, biomaterials, cold working, aging, hardness

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Tuning the strength and ductility balance of a TRIP titanium alloy

Cited by 44 publications

References 27 publications

Accommodation mechanisms in strain-transformable titanium alloys

Accommodation mechanisms in strain-transformable titanium alloys

First principles computation of composition dependent elastic constants of omega in titanium alloys: implications on mechanical behavior

Effect of thermomechanical treatment on structure and properties of metastable Ti-25Nb-8Sn alloy

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