Abstract
Boron segregation to grain boundaries was studied in ordered (B2) FeAl containing 40 at% Al. It was observed that small additions of boron (200 at ppm) change the fracture mode from intergranular to mixed (transgranular and intergranular). A low level of boron (few at%) was detected by AES in grain boundaries of this hypostoechiometric alloy. Nevertheless, the kinetic of boron segregation is rapid: even a quench from 950°C promotes it. As FeAl alloys are known to retain large concentrations of thermal vacancies, the possibility of an interaction between boron atoms and vacancies was investigated in order to understand the mechanism of boron segregation. Dilatometric isothermal experiments showed that vacancies eliminate more rapidly in B-doped Fe-40 at%Al than in B-free Fe-40 at%Al. Modelisation of the kinetics of vacancies elimination predict that complexes boron atoms - vacancies migrate more rapidly than free vacancies: the difference between their migration energies is higher than 0,4 eV. This result could justify the assumption that at least a part of boron segregation in FeAl is due to a non-equilibrium mechanism.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
