Unconventional solute-matrix bonding at metallic polycrystal grain boundaries and their amorphous counterparts

Abstract

The solute-matrix bonding is crucial to the solute segregation and mechanical properties of metals, but remains elusive for metallic polycrystal grain boundaries (GBs) and their amorphous counterparts. Herein, by unifying the effects of strain and bonding breaking, we identify a physical-based determinant that indicates an unusual Coulombic-like and localized nature of the metallic solute-matrix bonding at metallic polycrystal GBs and their amorphous counterparts. These unique bonding properties originate from the structural disorder with the solute effects as the secondary role. By further combining with the usual coordination number, atomic radius of solutes and matrices, and cohesive energy of matrices, we build an analytic framework to predict the segregation energies of metallic polycrystal GBs across various solutes and matrices, which can deduce previous computational and experimental findings. Our scheme not only uncovers the coupling rule of solutes and matrices at metallic polycrystal GBs and their glass counterparts, but also provides an effective tool for the design of high-performance alloys.