Abstract
ABSTRACTThe cohesion of a grain boundary (GB) is believed to be the controlling factor limiting theductility of high-strength metallic alloys, and particularly W. Intergranular embrittlement isusually associated with segregation of impurities at the GBs. Impurities present in ppmconcentrations can result in a dramatic decrease in plasticity. This paper reviews recent results onboth semi-empirical and first-principles modelling of the energetics and the electronic structuresof impurities on a Σ3 (111) GB in W. Our calculations have shown that impurities, such as N, O,P, S, and Si weaken the intergranular cohesion resulting in “loosening” the GB. The presence ofB and C on the contrary, enhances the interatomic interaction across the GB. The so-called site-competition effect should play an important role affecting impurity distribution in W GBs.Among the impurities analyzed, B in the GB has the lowest energy, and thus would tend todisplace other impurity atoms from the GB. Microalloying with 10-50 ppm B may be an effectiveway of improving tungsten's ductility. These results are important for understanding thefundamental physics of intergranular embrittlement.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: 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.