Physics – Condensed Matter – Materials Science
Scientific paper
2006-08-23
Physics
Condensed Matter
Materials Science
13 pages, 5 figures; Accepted in Phys. Rev. B
Scientific paper
10.1103/PhysRevB.74.155416
First principles calculations of the Sigma 5 (310)[001] symmetric tilt grain boundary in Cu with Bi, Na, and Ag substitutional impurities provide evidence that in the phenomenon of Bi embrittlement of Cu grain boundaries electronic effects do not play a major role; on the contrary, the embrittlement is mostly a structural or "size" effect. Na is predicted to be nearly as good an embrittler as Bi, whereas Ag does not embrittle the boundary in agreement with experiment. While we reject the prevailing view that "electronic" effects (i.e., charge transfer) are responsible for embrittlement, we do not exclude the role of chemistry. However numerical results show a striking equivalence between the alkali metal Na and the semi metal Bi, small differences being accounted for by their contrasting "size" and "softness" (defined here). In order to separate structural and chemical effects unambiguously if not uniquely, we model the embrittlement process by taking the system of grain boundary and free surfaces through a sequence of precisely defined gedanken processes; each of these representing a putative mechanism. We thereby identify three mechanisms of embrittlement by substitutional impurities, two of which survive in the case of embrittlement or cohesion enhancement by interstitials. Two of the three are purely structural and the third contains both structural and chemical elements that by their very nature cannot be further unravelled. We are able to take the systems we study through each of these stages by explicit computer simulations and assess the contribution of each to the nett reduction in intergranular cohesion. The conclusion we reach is that embrittlement by both Bi and Na is almost exclusively structural in origin; that is, the embrittlement is a size effect.
Finnis Michael W.
Lozovoi A. Y.
Paxton Anthony T.
No associations
LandOfFree
Structural and chemical embrittlement of grain boundaries by impurities: a general theory and first principles calculations for copper does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Structural and chemical embrittlement of grain boundaries by impurities: a general theory and first principles calculations for copper, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Structural and chemical embrittlement of grain boundaries by impurities: a general theory and first principles calculations for copper will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-109714