scholarly journals Phase-Field Modeling of Chemoelastic Binodal/Spinodal Relations and Solute Segregation to Defects in Binary Alloys

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1787
Author(s):  
Jaber Rezaei Mianroodi ◽  
Pratheek Shanthraj ◽  
Bob Svendsen ◽  
Dierk Raabe
Keyword(s):  
Spinodal Decomposition ◽  
Phase Field ◽  
Dislocation Line ◽  
Lattice Misfit ◽  
Solute Segregation ◽  
Solute Distribution ◽  
Solid Alloy ◽  
Solute Content ◽  
Dislocation Configuration ◽  
Precipitate Formation

Microscopic phase-field chemomechanics (MPFCM) is employed in the current work to model solute segregation, dislocation-solute interaction, spinodal decomposition, and precipitate formation, at straight dislocations and configurations of these in a model binary solid alloy. In particular, (i) a single static edge dipole, (ii) arrays of static dipoles forming low-angle tilt (edge) and twist (screw) grain boundaries, as well as at (iii) a moving (gliding) edge dipole, are considered. In the first part of the work, MPFCM is formulated for such an alloy. Central here is the MPFCM model for the alloy free energy, which includes chemical, dislocation, and lattice (elastic), contributions. The solute concentration-dependence of the latter due to solute lattice misfit results in a strong elastic influence on the binodal (i.e., coexistence) and spinodal behavior of the alloy. In addition, MPFCM-based modeling of energy storage couples the thermodynamic forces driving (Cottrell and Suzuki) solute segregation, precipitate formation and dislocation glide. As implied by the simulation results for edge dislocation dipoles and their configurations, there is a competition between (i) Cottrell segregation to dislocations resulting in a uniform solute distribution along the line, and (ii) destabilization of this distribution due to low-dimensional spinodal decomposition when the segregated solute content at the line exceeds the spinodal value locally, i.e., at and along the dislocation line. Due to the completely different stress field of the screw dislocation configuration in the twist boundary, the segregated solute distribution is immediately unstable and decomposes into precipitates from the start.

Phase-Field Modeling of Multiple Emulsions Via Spinodal Decomposition

Langmuir ◽  
2021 ◽  
Vol 37 (17) ◽  
pp. 5275-5281
Author(s):  
Haodong Zhang ◽  
Yanchen Wu ◽  
Fei Wang ◽  
Fuhao Guo ◽  
Britta Nestler
Keyword(s):  
Spinodal Decomposition ◽  
Phase Field ◽  
Phase Field Modeling ◽  
Multiple Emulsions ◽  
Field Modeling

Phase-field study of spinodal decomposition under the effect of grain boundary

2021 ◽  
Author(s):  
Ying-Yuan Deng ◽  
Can Guo ◽  
Jin-Cheng Wang ◽  
Qian Liu ◽  
Yu-Ping Zhao ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Field Study ◽  
Spinodal Decomposition ◽  
Phase Field

scholarly journals The Effects of Inhomogeneous Elasticity and Dislocation on Thermodynamics and the Kinetics of the Spinodal Decomposition of a Fe-Cr System: A Phase-Field Study

Metals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1209
Author(s):  
Wooseob Shin ◽  
Jeonghwan Lee ◽  
Kunok Chang
Keyword(s):  
Spinodal Decomposition ◽  
Phase Field ◽  
Early Stage ◽  
Field Method ◽  
Phase Field Method ◽  
Precipitate Size ◽  
System A ◽  
Phase Separation Kinetics ◽  
Cr Concentration ◽  
Cr System

The effects of inhomogeneous elasticity and dislocation on the microstructure evolution of α′ precipitate in a Fe-Cr system was investigated using a Computer Coupling of Phase Diagrams and Thermochemistry (CALPHAD)-type free energy incorporated phase-field method. In order to simulate the precipitation behavior by phase-field modeling in consideration of inhomogeneous elasticity, a Multiphysics Object-Oriented Simulation Environment (MOOSE) framework was used, which makes it easy to use powerful numerical means such as parallel computing and finite element method (FEM) solver. The effect of inhomogeneous elasticity due to the compositional inhomogeneity or the presence of dislocations affects the thermodynamic properties of the system was investigated, such as the lowest Cr concentration at which spinodal decomposition occurs. The effect of inhomogeneous elasticity on phase separation kinetics is also studied. Finally, we analyzed how inhomogeneous elasticity caused by compositional fluctuation or dislocation affects microstructure characteristics such as ratio between maximum precipitate size with respect to the average on early stage and later stage, respectively.

Strain Relaxation in Thin Films: the Effect of Dislocation Blocking

1999 ◽  
Vol 594 ◽  
Author(s):  
Peter J Goodhew
Keyword(s):  
Thin Films ◽  
Experimental Evidence ◽  
Strain Relaxation ◽  
Dislocation Line ◽  
Small Strain ◽  
Threading Dislocations ◽  
Semiconductor Films ◽  
Strained Layers ◽  
Dislocation Configuration ◽  
Perpendicular Line

AbstractThe relaxation of strained layers frequently occurs by the glide of threading dislocations. From very early on in the relaxation process, gliding dislocations will be forced to intersect a number of prior dislocations with almost-perpendicular line directions and their progress may be blocked. This effect has been widely reported in semiconductor films, and there is some experimental evidence that it is reduced when layers are grown on vicinal substrates. This implies that the blocking is sensitively dependent on the dislocation configuration and in particular on the dislocation line directions.In this paper the interactions between gliding threading dislocations and the perpendicular or nearly-perpendicular dislocation in their path are modelled quantitatively. The differences arising from different initial dislocation configurations and different predominant line directions are found to be small. Strain relaxation, at least in its early stages, should be virtually independent of the initial dislocation configuration.

Solute concentration dependence of strength and plastic instabilities in Al-Mg alloys

2005 ◽  
Vol 20 (2) ◽  
pp. 331-337 ◽  
Author(s):  
Gy. Horváth ◽  
N.Q. Chinh ◽  
J. Lendvai
Keyword(s):  
Dislocation Line ◽  
Solute Concentration ◽  
Mg Alloys ◽  
Dynamic Strain ◽  
Solute Content ◽  
Serrated Flow ◽  
Indentation Tests ◽  
Power Law Function ◽  
Chatelier Effect ◽  
Al Mg Alloys

Characteristics of the dynamic strain aging (DSA) in the Portevin-Le Chatelier effect are experimentally investigated by dynamic indentation tests and numerically analyzed by using literature models. Experimental results obtained on Al–Mg alloys show that the occurrence and development of the plastic instabilities—serrated indentation—depend strongly on the solute content. During dynamic microindentation tests the amplitude of microhardness drops—similarly to the global hardness—and is changing as a power law function of Mg solute content with an exponent of 2/3. It has been shown that the term describing the effect of DSA in serrated flow is not proportional but rather a power expression of the local solute concentration, Cs, on the dislocation line with the exponent of 1/2. Together with this, the kinetics of solute segregation during DSA is controlled by the pipe diffusion.

Microstructure evolution in multilayer c-TiAlN/TiN coatings during spinodal decomposition — A phase-field study

2016 ◽  
Vol 01 (01) ◽  
pp. 1650002 ◽  
Author(s):  
Jingjing Zhou ◽  
Lijun Zhang ◽  
Li Chen ◽  
Hong Wu ◽  
Yong Du
Keyword(s):  
Spinodal Decomposition ◽  
Microstructure Evolution ◽  
Phase Field ◽  
Phase Field Model ◽  
Dislocation Motion ◽  
Combined Model ◽  
Modulation Period ◽  
Tin Coatings ◽  
Good Agreement ◽  
Modulation Ratio

By means of the combined model, i.e., the phase-field model with finite interface dissipation in combination with the modified Cahn–Hilliard model, together with the materials parameters comprehensively verified in monolithic c-TiAlN coatings, the microstructure evolution in multilayer c-Ti[Formula: see text]Al[Formula: see text]N/TiN coatings annealed at [Formula: see text]C was quantitatively simulated by directly comparing with the experimental data. The sharp interface between c-TiN and c-Ti[Formula: see text]Al[Formula: see text]N layers in the as-deposited state was found to change into a diffuse one, which can act as highly effective obstacles against dislocation motion. Moreover, the simulations indicate that the spinodal decomposition occurs in the Ti[Formula: see text]Al[Formula: see text]N layer and the decomposed layer becomes thinner, which is in good agreement with the experimental observation. In addition, the effect of modulation period and modulation ratio on microstructure evolution in c-Ti[Formula: see text]Al[Formula: see text]N/TiN coating was further studied. The relatively smaller modulation period can generate more layers in the real scale of coatings, which can help to strengthen the coatings due to refinement of grains and restriction of dislocations. As for the modulation ratio, when the value decreases from 5:1 to 1:1, Ti atoms in the decomposed layer disappear faster. A further extension into a larger-sized simulation was also performed.

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