Pseudospinodal mechanism for fine α/β microstructures in β-Ti alloys

Boyne, A.; Wang, D.; Shi, Rongpei; Zheng, Yufeng; Behera, Amit; Nag, S.; Tiley, J.; Fraser, Hamish L.; Banerjee, Rajarshi; Wang, Y.

doi:10.1016/j.actamat.2013.10.026

Cited by 89 publications

(23 citation statements)

References 23 publications

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“…This effect leads to the formation of a composition-modulated structure across h1 0 0i b directions, which are elastically soft directions for bcc titanium and zirconium alloys [18,27]. In agreement with the present results, the spinodal decomposition mechanism was suggested to explain the homogeneous precipitation of fine a plates from the metastable b matrix of the analogous Ti-5Al-5Mo-5V-3Cr-0.5Fe, a Timetal 21S and Ti-V alloys [52][53][54]. These works state that the transformation is controlled by small compositional fluctuations in b, where lean and rich regions in solute evolve towards the equilibrium as the temperature increases.…”

Section: Spinodal Decomposition Of Bsupporting

confidence: 89%

Influence of phase transformation kinetics on the formation of α in a β-quenched Ti–5Al–5Mo–5V–3Cr–1Zr alloy

et al. 2015

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Section: Spinodal Decomposition Of Bsupporting

confidence: 89%

Influence of phase transformation kinetics on the formation of α in a β-quenched Ti–5Al–5Mo–5V–3Cr–1Zr alloy

et al. 2015

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“…bottom up to top regions). Given that the microstructural development for b-Ti alloys is highly sensitive to thermal history and their a phase nucleation process is far more complicated than a + b Ti-based alloys [19][20][21], it is necessary to examine the as-DLDed microstructures throughout the builds as the DLD process could cause different thermal effects in different regions.…”

Section: Introductionmentioning

confidence: 99%

Microstructural control during direct laser deposition of a β-titanium alloy

2015

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a b s t r a c tA concern associated with Direct Laser Deposition (DLD) is the difficulty in controlling microstructure due to rapid cooling rates after deposition, particularly in beta-Ti alloys. In these alloys, the beta-phase is likely to exist following DLD, instead of the desirable duplex alpha + beta microstructure that gives a good balance of properties. Thus, in this work, a parametric study was performed to assess the role of DLD parameters on porosity, build geometry, and microstructure in a beta-Ti alloy, Ti-5Al-5Mo-5V-3 Cr (Ti5553). The builds were examined using optical microscopy, scanning electron microscopy, and X-ray diffraction. Microhardness measurements were performed to assess the degree of re-precipitation of alpha-phase following an in situ dwelling and laser annealing procedure. The study identified several processing conditions that enable deposition of samples with the desired geometry and low porosity level. The microstructure was dominated by beta-phase, except for the region near the substrate where a limited amount of alpha-precipitates was present due to reheating effect. Although the microstructure was a mixture of equiaxed and columnar beta-grains alongside infrequent fine alpha-precipitates, the builds showed fairly uniform microhardness in different regions. In situ dwelling and annealing did not cause an obvious change in porosity, but did promote the formation of alpha-precipitates.

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“…The alloy composition was near where the free energy curves for the two phases, a and b, cross. [15] In the present simulation results, PSD was found in the early stages of c¢ precipitation in Ni-Al alloys.…”

Section: Introductionmentioning

confidence: 86%

“…It is qualitatively different than classical nucleation and growth [12,13] and also different than spinodal decomposition, The PSD mechanism was proposed by Khachaturyan firstly in nanostructure formation through phase decomposition. [14] Also Boyne et al [15] studied PSD in the formation of two-phase a + b microstructures in Ti alloys. The alloy composition was near where the free energy curves for the two phases, a and b, cross.…”

Section: Introductionmentioning

confidence: 98%

Effect of Diffusivity on the Pseudospinodal Decomposition of the γ′ Phase in a Ni-Al Alloy

Pang

Liu

et al. 2016

J. Phase Equilib. Diffus.

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The effect of diffusivity on pseudospinodal decomposition of c¢ (Ni 3 Al) phase precipitation was investigated in a Ni-Al alloy using the diffuse interface phase field model. The c¢ phase microstructure, coarsening dynamics and interfacial composition width between the c and c¢ phases were studied as a function of the diffusivity magnitude. Increasing the diffusivity results in a reduced number of c¢ nuclei, and accelerated growth and coarsening of the c¢ phase. The cube of the c¢ average radius versus time shows a linear relation during coarsening, and the Al concentration in the c matrix follow the relations Dc c Al $ t À1=3 regardless of the diffusivity magnitude. The c/c¢ interfacial composition width decreases with increased diffusivity and average radius. An obvious Al concentration depleted region is present at the c/c¢ interface during the nucleation and growth stage of c¢ phase indicates that growth occurs by down-hill diffusion in the matrix c phase. That combined with the gradual increase in c¢ composition demonstrates that pseudospinodal decomposition is the transformation mechanism.

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Pseudospinodal mechanism for fine α/β microstructures in β-Ti alloys

Cited by 89 publications

References 23 publications

Influence of phase transformation kinetics on the formation of α in a β-quenched Ti–5Al–5Mo–5V–3Cr–1Zr alloy

Influence of phase transformation kinetics on the formation of α in a β-quenched Ti–5Al–5Mo–5V–3Cr–1Zr alloy

Microstructural control during direct laser deposition of a β-titanium alloy

Effect of Diffusivity on the Pseudospinodal Decomposition of the γ′ Phase in a Ni-Al Alloy

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