The formation of ordered clusters in Ti–7Al and Ti–6Al–4V

Radecka, Anna; Bagot, P.A.J.; Martin, T.; Coakley, James A.; Vorontsov, V.A.; Moody, Michael P.; Ishii, H. A.; Rugg, David; Dye, David

doi:10.1016/j.actamat.2016.03.080

Cited by 53 publications

(30 citation statements)

References 33 publications

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“…b – d When applying ion beam milling, H atoms on the surface are implanted by the ion beam. At room temperature, H would then diffuse deep into specimen, and hydrides probably form and grow during milling process in case of pure Ti α phase (hydride formation is likely inhibited by Al addition in α phase 25,35 ). At cryogenic temperature, the beam damage and H implantation are slightly reduced and H diffusion is significantly suppressed.…”

Section: Resultsmentioning

confidence: 99%

Ti and its alloys as examples of cryogenic focused ion beam milling of environmentally-sensitive materials

et al. 2019

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Hydrogen pick-up leading to hydride formation is often observed in commercially pure Ti (CP-Ti) and Ti-based alloys prepared for microscopic observation by conventional methods, such as electro-polishing and room temperature focused ion beam (FIB) milling. Here, we demonstrate that cryogenic FIB milling can effectively prevent undesired hydrogen pick-up. Specimens of CP-Ti and a Ti dual-phase alloy (Ti-6Al-2Sn-4Zr-6Mo, Ti6246, in wt.%) were prepared using a xenon-plasma FIB microscope equipped with a cryogenic stage reaching −135 °C. Transmission electron microscopy (TEM), selected area electron diffraction, and scanning TEM indicated no hydride formation in cryo-milled CP-Ti lamellae. Atom probe tomography further demonstrated that cryo-FIB significantly reduces hydrogen levels within the Ti6246 matrix compared with conventional methods. Supported by molecular dynamics simulations, we show that significantly lowering the thermal activation for H diffusion inhibits undesired environmental hydrogen pick-up during preparation and prevents pre-charged hydrogen from diffusing out of the sample, allowing for hydrogen embrittlement mechanisms of Ti-based alloys to be investigated at the nanoscale.

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Section: Resultsmentioning

confidence: 99%

Ti and its alloys as examples of cryogenic focused ion beam milling of environmentally-sensitive materials

et al. 2019

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“…For example, APT studies have revealed the formation of α 2 precipitates of varying morphologies within the α case layer formed on Ti-6Al-4V [15] and have also investigated the relationship between mechanical properties and oxygen concentration in this alloy [16]. APT has also been used to study ordering [17][18][19], oxygen and carbon segregation [20] and fine scale precipitation [21][22][23] in a range of titanium alloys.…”

Section: Introductionmentioning

confidence: 99%

Quantifying the effect of oxygen on micro-mechanical properties of a near-alpha titanium alloy

Gardner

Gopon

Magazzeni

et al. 2021

Journal of Materials Research

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Titanium alloys are widely used in the aerospace industry, yet oxygen ingress can severely degrade the mechanical properties of titanium alloy components. Atom probe tomography (APT), electron probe microanalysis (EPMA) and nanoindentation were used to characterise the oxygen-rich layer on an in-service jet engine compressor disc, manufactured from the titanium alloy TIMETAL 834. Oxygen ingress was quantified and related to changes in mechanical properties through nanoindentation studies. The relationship between oxygen concentration, microstructure, crystal orientation and hardness has been explored through correlative hardness mapping, EPMA and electron backscatter diffraction (EBSD). It has been found that the hardening effects of microstructure and crystallography are only significant at very low-oxygen concentrations, whereas interstitial solid solution hardening dominates by order of magnitude for higher oxygen concentrations. The role of microstructure on oxygen ingress has been studied and oxygen ingress along a potential α/β interface was directly observed on the nanoscale using APT.

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“…The solvus for a 2 is between 550°C and 600°C for Ti-6Al-4V, about 650°C for Ti-6242 and about 750°C for IMI834. [2] This phase precipitates for prolonged ageing treatments at low temperatures [62][63][64] or low cooling rates. [65] A slight reduction in the c/a ratio and a noticeable increase in Young's modulus have been reported during ageing below these temperatures.…”

Section: Critical Resolved Shear Stresses In the A Phasementioning

confidence: 99%

Microplasticity at Room Temperature in α/β Titanium Alloys

Hémery

Villechaise

Banerjee

2020

Metall Mater Trans A

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The current understanding of room temperature microplasticity in a/b titanium alloys is reviewed with a special emphasis on dual-phase engineering alloys. As the interplay between microstructure and deformation mechanisms governs both the microscale and macroscale mechanical response, a brief description of the main features of a/b microstructures is first provided. Elastic and plastic deformation in individual phases is then described. The complex interactions that govern the effect of grain boundaries, phase interfaces and microtexture on deformation behaviour are reviewed. Crystal plasticity simulations have evolved over the past decade as a key technique to obtain a mechanistic understanding of the deformation of Ti alloys. Micromechanical aspects are emphasized with a discussion of input parameters required to achieve realistic constitutive modeling. As microplasticity is especially relevant in cyclic loading such as experienced in-service by components, the current understanding of the relation of this regime with fatigue and dwell-fatigue behavior is briefly summarized in the final section.

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The formation of ordered clusters in Ti–7Al and Ti–6Al–4V

Cited by 53 publications

References 33 publications

Ti and its alloys as examples of cryogenic focused ion beam milling of environmentally-sensitive materials

Ti and its alloys as examples of cryogenic focused ion beam milling of environmentally-sensitive materials

Quantifying the effect of oxygen on micro-mechanical properties of a near-alpha titanium alloy

Microplasticity at Room Temperature in α/β Titanium Alloys

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