First-principles investigation on the interaction of Boron atom with nickel part II: Absorption and diffusion at grain boundary

Abstract

Abstract In this work, Boron atom absorption and diffusion behaviors at Σ3(111) [ 1 − 10 ] and Σ5(210)[001] grain boundaries (GBs) were studied with a first-principles density functional theory and the climbing image nudged elastic band method. The calculation results reveal that the two GBs show the markedly different interaction behavior with atomic Boron. The close-packed Σ3 GB plays the negative role for absorbing B atom and can accelerate the B atom diffusion, while the Σ5 GB plays the positive role for absorbing B atom and acts as a two-dimensional diffusion barrier. The ability for Ni GBs and Ni bulk to absorb B atom is controlled by the electron density ρ el at the site before inserting the B atom, and a certain range of ρ el plays the positive role for absorbing B atom, while the larger or smaller ρ el outside the certain range will both no longer have the same influence. The different energy barrier for B atom diffusing leads to the huge different diffusion rate, in which, the diffusion rate for B atom along the Σ3 GB is two orders of magnitude greater than that in the bulk Ni and nearly four orders of magnitude greater than that across the Σ5 GB.