Screw dislocation structure and mobility in body centered cubic Fe predicted by a Gaussian Approximation Potential

作     者：Francesco Maresca Daniele Dragoni Gábor Csányi Nicola Marzari William A.Curtin 

作者机构：Laboratory for Multiscale Mechanics Modeling(LAMMM)Institute of Mechanical EngineeringÉcole Polytechnique Fédérale de LausanneLausanne CH-1015Switzerland Theory and Simulation of Materials(THEOS)and National Centre for Computational Design and Discovery of Novel Materials(NCCR MARVEL)École Polytechnique Fédérale de LausanneLausanne CH-1015Switzerland Dipartimento di Scienza dei MaterialiUniversitàdi Milano-BicoccaVia R.Cozzi 55Milan I-20125Italy Department of EngineeringUniversity of CambridgeTrumpington StreetCambridge CB21PZUK 

出 版 物：《npj Computational Materials》 (计算材料学（英文）)

年 卷 期：2018年第4卷第1期

页      面：90-96页

核心收录：

学科分类：08[工学] 080502[工学-材料学] 0805[工学-材料科学与工程（可授工学、理学学位）] 

基　　金：F.M.and W.A.C.acknowledge support of this work through a European Research Council Advanced Grant,Predictive Computational Metallurgy,ERC grant agreement no.339081 PreCoMet D.D.and N.M.acknowledge SNSF Project No.200021-143636 and NCCR MARVEL G.C.acknowledges funding from the EPSRC under Programme Grant EP/L014742/1 

主　　题：structure dislocation cubic 

摘      要：The plastic flow behavior of bcc transition metals up to moderate temperatures is dominated by the thermally activated glide of screw dislocations,which in turn is determined by the atomic-scale screw dislocation core structure and the associated kink-pair nucleation mechanism for *** complex plasticity phenomena requires the simulation of many atoms and interacting dislocations and *** sizes are beyond the scope of first-principles methods and thus require empirical interatomic *** for the technological important case of bcc Fe,existing empirical interatomic potentials yield spurious ***,the structure and motion of the screw dislocations in Fe are studied using a new Gaussian Approximation Potential(GAP)for bcc Fe,which has been shown to reproduce the potential energy surface predicted by density-functional theory(DFT)and many associated *** Fe GAP predicts a compact,non-degenerate core structure,a single-hump Peierls potential,and glide on{110},consistent with DFT *** thermally activated motion at finite temperatures occurs by the expected kink-pair nucleation and propagation *** stress-dependent enthalpy barrier for screw motion,computed using the nudgedelastic-band method,follows closely a form predicted by standard theories with a zero-stress barrier of~1 eV,close to the experimental value of 0.84 eV,and a Peierls stress of~2 GPa consistent with DFT predictions of the Peierls potential.