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.

Numerical Simulation of Spinodal Deposition in Cu–6at.%Ni–3at.%Si Ternary Alloy Using of Phase Field Method

2011 ◽  
Vol 704-705 ◽  
pp. 1410-1415 ◽  
Author(s):  
Yong Qiang Long ◽  
Ping Liu ◽  
Yong Liu ◽  
Shu Guo Jiao ◽  
Bao Hong Tian
Keyword(s):  
Spinodal Decomposition ◽  
Ternary Alloy ◽  
Phase Field ◽  
Elastic Energy ◽  
Early Stage ◽  
Phase Field Model ◽  
Field Method ◽  
Phase Field Method ◽  
Growth Exponent ◽  
Dynamics Calculation

Based on Cahn-Hilliard nonlinear diffusion equation, the phase field model has been established for ternary alloy spinodal decomposition, which directly couples with Calphad thermodynamics and dynamics calculation and takes into account the effect of the coherent elastic energy. The simulated microstructures of spinodal decomposition were carried out in the isothermally-aged of Cu-6at.%Ni-3at.%Si alloy. The results indicate that the spinodal decomposition takes place at the early stage of Cu-6at.%Ni-3at.%Si alloy aging at temperatures of 723K, forming two-phases mixture of Cu-rich and Ni/Si-rich, and the decomposition microstructures are distributed in a semi-interconnected labyrinth-like form. Under the effect of the coherent elastic energy, the decomposition microstructures demonstrate the obvious anisotropic characteristics, and present interconnected rectangular stripes aligned along [10] and [01] directions. The growth of the decomposition microstructures is in accordance with the growth law of growth exponentn≈0.29, slightly less than the LSW’s prediction.

Computer Simulation of the Early Stage of Precipitation of L12-Ni3(Al,V) Using Microscopic Phase Field Method

2015 ◽  
Vol 817 ◽  
pp. 809-815
Author(s):  
Wei Ping Dong ◽  
Zheng Chen
Keyword(s):  
Spinodal Decomposition ◽  
Phase Field ◽  
Early Stage ◽  
Equilibrium Phase ◽  
Field Method ◽  
Phase Field Method ◽  
Precipitation Process ◽  
Interatomic Potentials ◽  
Precipitation Mechanism ◽  
Precipitation Phase

Based on the phase field theory, the long-range order (LRO) parameter related interatomic potentials equations were utilized to calculate the interatomic potentials of L10-Ni3(Al,V), L12-Ni3Al and L12-Ni3(Al,V) phases varying with temperature and concentrations. Using these potentials, the simulated microstructure evolution and the order parameter with the time of Ni75Al20V5 ternary alloy are simulated at temperature 1000K during the early stage of the precipitation process in this research. Results testify that the precipitation sequence during the early stage of Ni75Al20V5 alloy is the disordered phase →L10 pre-precipitation phase →L12 equilibrium phase. Firstly, the nonstoichiometric L10 pre-precipitation phase formed by congruent ordering precipitation mechanism; secondly, the nonstoichiometric L12 phase formed by transforming from L10 phase; thirdly, the stoichiometric equilibrium L12 phase formed by spinodal decomposition precipitation mechanism. It is discovered that the precipitation mechanism (congruent ordering+ spinodal decomposition) process was closely related to free energy and interatomic potentials: L10 pre-precipitation phase’s free energies are higher and interatomic potentials are smaller than those of L12 equilibrium phase.

Investigation of Spinodal Decomposition in Fe-Cr Alloys: CALPHAD Modeling and Phase Field Simulation

2011 ◽  
Vol 172-174 ◽  
pp. 1060-1065 ◽  
Author(s):  
Wei Xiong ◽  
Klara Asp Grönhagen ◽  
John Ågren ◽  
Malin Selleby ◽  
Joakim Odqvist ◽  
...  
Keyword(s):  
Spinodal Decomposition ◽  
Phase Field ◽  
Accurate Determination ◽  
Enthalpy Of Mixing ◽  
Field Method ◽  
Phase Field Method ◽  
Phase Field Simulation ◽  
Mobility Data ◽  
Field Simulation ◽  
Calphad Modeling

This work is dedicated to simulate the spinodal decomposition of Fe-Cr bcc (body centered cubic) alloys using the phase field method coupled with CALPHAD modeling. Thermodynamic descriptions have been revised after a comprehensive review of information on the Fe-Cr system. The present work demonstrates that it is impossible to reconcile the ab initio enthalpy of mixing at the ground state with the experimental one at 1529 K using the state-of-the-art CALPHAD models. While the phase field simulation results show typical microstructure of spinodal decomposition, large differences have been found on kinetics among experimental results and simulations using different thermodynamic inputs. It was found that magnetism plays a key role on the description of Gibbs energy and mobility which are the inputs to phase field simulation. This work calls for an accurate determination of the atomic mobility data at low temperatures.

scholarly journals Deep Learning Approach for Chemistry and Processing History Prediction from Materials Microstructure: Application to Spinodal Decomposition

2021 ◽  
Author(s):  
Amir Abbas Kazemzadeh Farizhandi ◽  
Omar Betancourt ◽  
Mahmood Mamivand
Keyword(s):  
Feature Extraction ◽  
Deep Learning ◽  
Chemical Composition ◽  
Spinodal Decomposition ◽  
Phase Field ◽  
Field Method ◽  
Phase Field Method ◽  
Processing Temperature ◽  
Learning Approach ◽  
Processing History

Abstract Finding the chemical composition and processing history from a microstructure morphology for heterogeneous materials is desired in many applications. While the simulation methods based on physical concepts such as the phase-field method can predict the spatio-temporal evolution of the materials’ microstructure, they are not efficient techniques for predicting processing and chemistry if a specific morphology is desired. In this study, we propose a framework based on a deep learning approach that enables us to predict the chemistry and processing history just by reading the morphological distribution of one element. As a case study, we used a dataset from spinodal decomposition simulation of Fe-Cr-Co alloy created by the phase-field method. The mixed dataset, which includes both images, i.e., the morphology of Fe distribution, and continuous data, i.e., the Fe minimum and maximum concentration in the microstructures, are used as input data, and the spinodal temperature and initial chemical composition are utilized as the output data to train the proposed deep neural network. The proposed convolutional layers were compared with pretrained EfficientNet convolutional layers as transfer learning in microstructure feature extraction. The results show that the trained shallow network is effective for chemistry prediction. However, accurate prediction of processing temperature requires more complex feature extraction from the morphology of the microstructure. We benchmarked the model predictive accuracy for real alloy systems with a Fe-Cr-Co transmission electron microscopy micrograph. The predicted chemistry and heat treatment temperature were in good agreement with the ground truth.

Phase-Field Model for Spinodal Decomposition of Dilute Solute Field in Al-Ag Alloy

2011 ◽  
Vol 415-417 ◽  
pp. 1168-1170
Author(s):  
Ying Jun Gao ◽  
Zhi Rong Luo
Keyword(s):  
Free Energy ◽  
Spinodal Decomposition ◽  
Phase Field ◽  
Phase Field Model ◽  
Free Energy Density ◽  
Field Method ◽  
Energy Functional ◽  
Phase Field Method ◽  
Fourth Power ◽  
Free Zone

The typical Landau free energy functional with the fourth power of a solute composition field is not suitable for representing spinodal decomposition of a dilute Ag solute field in Al-Ag alloy. Facing this challenge, a new free energy density function is proposed for spinodal decomposition of a dilute Ag solute field of Al-Ag alloy. The evolution of the solute field in Al-4.2% Ag alloy is studied by phase-field method using this new function. The simulated results reveal that the precipitate free zone (PFZ) around the precipitated phase is an ellipse and its width is about two times that of phase, while in the region far from PFZ, a GPZ pattern of Ag solute field appears due to spinodal decomposition.

scholarly journals Effect of irradiation-induced cascade mixing on spinodal decomposition in U–Nb and U–Zr alloys: a phase field study

RSC Advances ◽  
2021 ◽  
Vol 11 (59) ◽  
pp. 37612-37623
Author(s):  
Yong Lu ◽  
Honghao Guo ◽  
Hengfeng Gong ◽  
Zheng Jiang ◽  
Xiaoyi Huang ◽  
...  
Keyword(s):  
Equilibrium State ◽  
Field Study ◽  
Spinodal Decomposition ◽  
Phase Field ◽  
Field Method ◽  
Phase Field Method ◽  
Simulation Results ◽  
Method Show ◽  
Zr Alloys

The simulation results of phase-field method show that the cascade mixing can drive Nb or Zr atoms back into solution until a new equilibrium state between local cascade mixing and spinodal decomposition is reached.

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