Nanoscale Phase Evolution during Continuum Decomposition of Fe-Cr Alloys

Abstract

The continuum decomposition of the Fe-Cr alloys from initial phase separation to steady-state coarsening with concentrations varying from 25 at % Cr and 30 at % Cr to 33 at % Cr aged at 750 K was studied by utilizing three-dimensional phase-field simulations. The dynamic stages of separation of nanoscale Cr-enriched α′ phase were distinguished by the evolution of the volume fraction, particle number density and the average particle radius of the α′ phase. The stage of steady-state coarsening was characterized with an equilibrium volume fraction and decreasing particle number density. The coarsening rate constant by linear fitting of the cube of average radius and aging time shows an increase with the increasing Cr concentration. The time exponents decrease from the growth and coarsening stage to the steady-state coarsening stage and show a dependence on the particles number density at different concentrations. The quantitative evolutions of α′ phase via nucleation growth and spinodal decomposition are theoretically helpful for understanding the microstructure evolution with aging time in Fe-Cr alloys.

Quantitative Phase-Field Simulation of Composition Partition and Separation Kinetics of Nanoscale Phase in Fe-Cr-Al Alloy

“…In the past few decades, more attention has been paid to Fe-Cr binary alloys to understand phase decomposition by experiments and computer simulations [16][17][18][19][20][21]. As a new potential alloy in nuclear plants, Fe-Cr-Al alloys attracted much attention and were studied by utilizing the computer coupling of phase diagrams and thermochemistry formulation.…”

Thermal Properties Investigation of FeCr Alloy Using Lammps Simulation: A Preliminary Study

“…Although many intensive studies on Fe-Cr alloys have been carried out, there are still many things that need to be explored both experimentally and computer simulations such as the diffusion of Fe and Cr under different temperature conditions 5) , to understand and quantify the kinetics and mechanisms of microstructure and property evolution of Fe-Cr alloys under various thermal and ionizing radiation environments etc. 5,6,7,8) Some experimental research works on Radial Distribution Function (RDF) using XRD or neutron scattering method have been conducted for different materials 9,10,11) . Pair-distribution function (PDF) analyses or Radial distribution function can be carried out on organic and organometallic compounds from powder electron diffraction data.…”

Generalized non-classical nucleation model in binary alloys

“…NCNT is based on free energy density functional theory (see also [1][2][3]) and allows to calculate composition profile of critical nucleus and nucleation barrier, but nucleation rate is defined with application of some relations borrowed from CNT [1-3, 5, 6]. Finally, the CH approach has been transformed to well-known theory of spinodal decomposition [7,8] that is mainly employed for simulation of the first order phase transitions in area of non-stable states [9][10][11][12]. The CH equation formulated in theory of spinodal decomposition can be also applied for process of nucleation [12][13][14].…”

“…Finally, the CH approach has been transformed to well-known theory of spinodal decomposition [7,8] that is mainly employed for simulation of the first order phase transitions in area of non-stable states [9][10][11][12]. The CH equation formulated in theory of spinodal decomposition can be also applied for process of nucleation [12][13][14]. Simulation of nucleation by the equation demands to account fluctuations that is responsible for overcoming of nucleation barrier.…”