Phase-Field Investigation of Multicomponent Diffusion in Single-Phase and Two-Phase Diffusion Couples

Historically, metals exhibit superplasticity only while forming in a two-phase field because a two-phase microstructure helps ensure a fine, stable grain size. In the U-5.8 Nb alloy, superplastici ty exists for up to 2 h in the single phase field (γ1) at 670°C. This is above the equilibrium monotectoid temperature of 647°C. Utilizing dilatometry, the superplastic (SP) U-5.8 Nb alloy requires superheating to 658°C to initiate the α+γ2 → γ1 transformation at a heating rate of 1.5°C/s. Hence, the U-5.8 Nb alloy exhibits an anomolous superplastic behavior.

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Interface Movement and Microstructure Evolution of Interdiffusion in the Binary Alloy Diffusion Couples

Materials Science Forum ◽

10.4028/www.scientific.net/msf.689.123 ◽

2011 ◽

Vol 689 ◽

pp. 123-129

Author(s):

Yong Sheng Li ◽

Yan Zhou Yu ◽

Xiao Lin Cheng ◽

Guang Chen

Keyword(s):

Single Phase ◽

Relative Concentration ◽

Equilibrium Concentration ◽

Diffusion Couples ◽

Binary Diffusion ◽

Two Phase ◽

Concentration Difference ◽

Initial Concentration ◽

Interdiffusion Flux ◽

Interface Movement

The phase field simulation of interface movement and interdiffusion microstructure in a binary diffusion couples was developed. The diffusion couples with nonequilibrium concentration for single phase or single phase and two-phase including the temperature and mobility effects were studied. It’s shown that the interface movement and the atoms diffusion direction were determined by the magnitude of relative concentration difference between the initial concentration and the equilibrium concentration, the distance of interface movement and interdiffusion flux increases as the temperature or the mobility increasing, and the large mobility makes the particles coarsening faster.

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Influence of the ledge mechanism of diffusivities back-calculated from the migration kinetics of planar interphase boundaries in two-phase diffusion couples

Scripta Metallurgica ◽

10.1016/0036-9748(89)90092-6 ◽

1989 ◽

Vol 23 (1) ◽

pp. 55-58 ◽

Cited By ~ 3

Author(s):

M. Enomoto ◽

H.I. Aaronson

Keyword(s):

Diffusion Couples ◽

Two Phase ◽

Phase Diffusion ◽

Interphase Boundaries ◽

Kinetics Of ◽

Ledge Mechanism

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Interdiffusion Microstructure Maps for Two Phase Diffusion Couples

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.72.105 ◽

2000 ◽

Vol 72 ◽

pp. 105-110

Author(s):

John Morral ◽

Hui Min Chen ◽

F. Meisenkothen

Keyword(s):

Diffusion Couples ◽

Two Phase ◽

Phase Diffusion

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Assessment of Ternary Multicomponent Diffusion in Alloy 22 (Ni-Cr-Mo)

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.266.181 ◽

2007 ◽

Vol 266 ◽

pp. 181-190 ◽

Cited By ~ 1

Author(s):

A.V. Jaques ◽

J.C. LaCombe

Keyword(s):

Optimization Problem ◽

Single Phase ◽

Multicomponent Diffusion ◽

Diffusion Couples ◽

Profile Data ◽

Alloy 22 ◽

Constant Diffusivity ◽

Point Composition ◽

Potential Use

Diffusivity [D] matrices are reported for the ternary Ni-Cr-Mo alloy in the approximate single-phase compositional range of Hastelloy C-22 (Alloy 22), surrounding Ni-63 wt.%, Cr-22.3 wt.%, and Mo-14.7 wt.%. These data will contribute to our understanding of the long-term phase stability of Alloy 22, and its potential use as a corrosion barrier in nuclear waste packages. Experimental diffusion couple data were obtained at selected temperatures from a series of diffusion couples, and evaluated, assuming constant diffusivity. Our approach treats the process as an optimization problem that simultaneously considers concentration profile data from numerous diffusion couples surrounding a single end-point composition. We make use of the mathematical characteristics of the analytical solution to this problem, reducing the number of parameters to be fitted. The parameter fitting is accomplished using a combination of heuristic and deterministic methods. Discussion of the sources and magnitudes of uncertainty in the diffusivity values is included.

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