Effect of Fe Content on the As-Cast Microstructures of Ti–6Al–4V–xFe Alloys

Ding, Lei; Hu, Rui; Gu, Yulei; Zhou, Danying; Chen, Fuwen; Zhou, Lian; Chang, Hui

doi:10.3390/met10080989

Cited by 8 publications

(2 citation statements)

References 20 publications

(24 reference statements)

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“…Random high angle GBs in Ti have been shown to be stabilized by the segregation of Fe in the substitutional sites [24]. Fe segregation has also been reported in commercial Ti alloys with no analysis of the influence of GB type on the segregation behaviour [69,25,70]. In the present study, Fe was observed to segregate preferentially in few selected symmetric facets in Σ13 (0001) Ti GB, as seen in Fig.…”

Section: Grain Boundary Segregationsupporting

confidence: 67%

Microstructure, grain boundary evolution and anisotropic Fe segregation in (0001) textured Ti thin films

Devulapalli¹,

Hans²,

Prithiv³

et al. 2021

Preprint

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The structure and chemistry of grain boundaries (GBs) are crucial in determining polycrystalline materials' properties. Faceting and solute segregation to minimize the GB energy is a commonly observed phenomenon. In this paper, a deposition process to obtain pure tilt GBs in titanium (Ti) thin films is presented. By increasing the power density, a transition from polycrystalline film growth to a maze bicrystalline Ti film on SrTiO 3 (001) substrate is triggered. All the GBs in the bicrystalline thin film are characterized to be Σ13 [0001] coincident site lattice (CSL) boundaries. The GB planes are seen to distinctly facet into symmetric { 7520} and asymmetric {10 10} // {11 20} segments of 20-50 nm length. Additionally, EDS reveals preferential segregation of iron (Fe) in every alternate symmetric { 7520} segment. Both the faceting and the segregation are explained by a difference in the CSL density between the facet planes. Furthermore, in the GB plane containing Fe segregation, atom probe tomography is used to experimentally determine the GB excess solute to be 1.25 atoms/nm 2 . In summary, the study reveals for the first time a methodology to obtain bicrystalline Ti thin films with strong faceting and an anisotropy in iron (Fe) segregation behaviour within the same family of planes.

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Section: Grain Boundary Segregationsupporting

confidence: 67%

Microstructure, grain boundary evolution and anisotropic Fe segregation in (0001) textured Ti thin films

Devulapalli¹,

Hans²,

Prithiv³

et al. 2021

Preprint

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“…The advantages and disadvantages of such treatment were analyzed for expanding the database of possible β-Ti bio-alloys that could be used, depending on the specific requirements of different biomedical implant applications. Ding et al [8] evaluated the solidification microstructure of Ti-6Al-4V-xFe (x = 0.1, 0.3, 0.5, 0.7 and 0.9) alloys fabricated by levitation melting. The growth of grains in the function of Fe content, as well as the composition distribution mechanisms during the solidification process of the alloy, were discussed.…”

Section: Development Of Microstructure and Operational Propertiesmentioning

confidence: 99%

Titanium Alloys and Titanium-Based Matrix Composites

Motyka

2021

Metals

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Achieving a Columnar-to-Equiaxed Transition Through Dendrite Twinning in High Deposition Rate Additively Manufactured Titanium Alloys

Davis,

Wainwright,

Sahu

et al. 2024

Metall Mater Trans A

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The coarse β-grain structures typically found in titanium alloys like Ti–6Al–4V (wt pct, Ti64) and Ti–6Al–2Sn–4Zr–2Mo–0.1Si (Ti6242), produced by high deposition rate additive manufacturing (AM) processes, are detrimental to mechanical performance. Certain modified processing conditions have been shown to lead to a more refined grain structure, which has generally been attributed to a change in the solidification conditions with respect to the experimental Hunt diagram proposed by Semiatin and Kobryn. It is shown that with Wire Arc AM (WAAM) increasing the wire feed speed (WFS) is effective in promoting a columnar-equiaxed transition (CET). Conversely, estimates of the dendrite-tip undercooling using the KGT model suggest that this will be too small for free nucleation without the addition of artificial nucleants, due to the very low solute partitioning in Ti alloys. It is also shown that it is difficult to promote a CET with plasma transferred arc WAAM as computational fluid dynamics (CFD) melt-pool simulations indicate that the solidification parameters remain within the columnar region on the Semiatin-Kobryn Hunt map, within the constraints of a stable process. However, a high fraction of twin boundaries was observed in the refined β-grain structures seen at high WFS. This has been attributed to departure of $$\left\langle {001} \right\rangle _{\beta }$$ 001 β alignment from the direction of maximum thermal gradient, caused by the curvature of the fusion boundary, stimulating dendrite twinning during solidification. In addition, it is shown that increasing the WFS leads to a change in melt-pool geometry and a reduction of remelt depth, which promoted dendrite twinning and grain refinement.

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Effect of Fe Content on the As-Cast Microstructures of Ti–6Al–4V–xFe Alloys

Cited by 8 publications

References 20 publications

Microstructure, grain boundary evolution and anisotropic Fe segregation in (0001) textured Ti thin films

Microstructure, grain boundary evolution and anisotropic Fe segregation in (0001) textured Ti thin films

Titanium Alloys and Titanium-Based Matrix Composites

Achieving a Columnar-to-Equiaxed Transition Through Dendrite Twinning in High Deposition Rate Additively Manufactured Titanium Alloys

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