Solute segregation at grain boundaries

Abstract

This feature article summarizes the present art and science of grain boundary segregation from the viewpoint of the authors activities in this field. In the part on equilibrium segregation, fundamental effects on grain boundary segregation are discussed such as the nature of the solute/matrix binary system, presence of additional elements, temperature, grain boundary orientation and type of interface. In addition, the predictive capabilities of grain boundary segregation diagrams are outlined. The present models of segregation kinetics are reviewed and discussed in connection with recent experiment. The last part of the paper is focussed on the most important c3nsequences of grain boundary segregation, i.e., grain boundary cohesion and fracture.

Adhesion of Copper and Alumina from First Principles

“…13 It has been shown 13 that trends in interface stability are not significantly affected by temperatures up to 1300 K. Hydrogen zero-point energies in the bulk and surface of copper have been found 24 to differ by ϳ0.04 eV. Entropy contributions to heats of segregation to metallic grain boundaries have been estimated 25,26 to be Ϫ3k Յ ⌬S Յ 3k, where k is the Boltzmann constant, i.e., at 300 K, only ϳ0.07 eV per atom contribution to the heat of segregation. All these temperature effects are too small to affect our conclusions in the following.…”

Correlation Between Grain‐Boundary Segregation and Grain‐Boundary Plane Orientation in Nb‐Doped TiO2

“…Although there has been some previous research on GB segregation as a function of GB misorientation by both experimental and computer simulation approaches, only special grain boundaries and limited numbers of general grain boundaries have been examined. [1][2][3] Thus, an adequate picture of the variation of GB segregation over the entire GB orientation space is still lacking. Furthermore, the anisotropy of GB chemistry and its orientation dependence have been less thoroughly probed in ceramics than in metals.…”

Present Status of Microstructural Characterization of Steel by Analytical Methods

“…AES is used for analyzing a microscopic area by using a sharply focused electron beam, and for obtaining depth proi~iles in Is). Grain boundary segregation has sometimes been studied by analyzing the surface of samples fractured in an ultra high vacuum by AES l',20). Since electron beams in AES can usually be focussed to less than about one micronmeter, segregation at each grain boundary is analyzed by AES.…”