Solute-atom segregation at internal interfaces on an atomic scale: atom-probe experiments and computer simulations

This paper addresses fundamental questions concerning the determination of the chemical compositions of internal interfaces (grain boundaries)-in single-phase f.c.c. or b.c.c. binary alloys-and the relationships of the solute enhancement factor at a grain boundary to its structure. This goal is achieved utilizing three principal techniques: (i) atom-probe field-ion microscopy; (ii) transmission electron microscopy; and (iii) Monte Carlo computer simulations that utilize embedded atom method potentials for f.c.c. alloys. Atom-probe field-ion microscopy is used to determine the chemical composition of an interface, and transmission electron microscopy is employed to determine its five macroscopic degrees of freedom. The Monte Carlo simulations employ the Metropolis et al. algorithm to simulate segregation in the Pt(Au) and Pt(Ni) systems. Detailed experimental and computer simultation results are presented for grain boundaries in Pt(Au), Pt(Ni) and W(Re) primary solid-solution alloys.