Calculation of cohesion and changes in electronic structure due to impurity segregation at boundaries in iron

It is well known that impurities in iron which segregate to grain boundarie s can dramatically change physical properties. Carbon and boron tend to inc rease ductility while phosphorous and sulphur lead to embrittlement. Cohesi on at boundaries in iron can be understood by studying changes in the iron d states responsible for bonding. Since the effects are quite localised, re latively small systems can be used to model the electronic structure. Both FLAPW and LKKR calculations show that the average energy of the d band is l ower for B and C impurities and higher for P and S impurities. These result s are consistent with (C) 1999 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All the macroscopic changes in cohesion. rights reserved.