Segregation-assisted spinodal and transient spinodal phase separation at grain boundaries  

作　　者：Reza Darvishi Kamachali Alisson Kwiatkowski da Silva Eunan McEniry Dirk Ponge Baptiste Gault Jörg Neugebauer Dierk Raabe 

机构地区：[1]Federal Institute for Materials Research and Testing(BAM),Unter den Eichen 87,12205 Berlin,Germany [2]Max-Planck-Institut für Eisenforschung GmbH,Max-Planck-Straße 1,40237 Düsseldorf,Germany [3]Department of Materials,Royal School of Mines,Imperial College,Prince Consort Road,London SW72BP,UK

出　　处：《npj Computational Materials》2020年第1期76-88,共13页计算材料学（英文）

基　　金：Reza Darvishi Kamachali gratefully acknowledges financial support from the German Research Foundation(DFG)under the project DA 1655/2-1 within the Heisenberg program;A.Kwiatkowski da Silva is grateful to the Brazilian National Research Council(Conselho Nacional de Pesquisas,CNPQ)for the scholarship through the Science without Borders Project(203077/2014-8).

摘　　要：Segregation to grain boundaries affects their cohesion,corrosion,and embrittlement and plays a critical role in heterogeneous nucleation.In order to quantitatively study segregation and low-dimensional phase separation at grain boundaries,here,we apply a density-based phase-field model.The current model describes the grain-boundary thermodynamic properties based on available bulk thermodynamic data,while the grain-boundary-density profile is obtained using atomistic simulations.To benchmark the performance of the model,Mn grain-boundary segregation in the Fe–Mn system is studied.3D simulation results are compared against atom probe tomography measurements conducted for three alloy compositions.We show that a continuous increase in the alloy composition results in a discontinuous jump in the segregation isotherm.The jump corresponds to a spinodal phase separation at grain boundary.For alloy compositions above the jump,we reveal an interfacial transient spinodal phase separation.The transient spinodal phenomenon opens opportunities for knowledge-based microstructure design through the chemical manipulation of grain boundaries.The proposed density-based model provides a powerful tool to study thermodynamics and kinetics of segregation and phase changes at grain boundaries.

关 键 词：GRAIN alloy SEPARATION 

分 类 号：TB30[一般工业技术—材料科学与工程]