Solute segregation kinetics and dislocation depinning in a binary alloy

Abstract

Static strain aging, a phenomenon caused by diffusion of solute atoms to dislocations, is an important contributor to the strength of substitutional alloys. Accurate modeling of this complex process requires both atomic spatial resolution and diffusional time scales, which is very challenging to achieve with commonly used atomistic computational methods. In this paper, we use the recently developed "diffusive molecular dynamics" (DMD) method that is capable of describing the kinetics of the solute segregation process at the atomic level while operating on diffusive time scales in a computationally efficient way. We study static strain aging in the Al-Mg system and calculate the depinning shear stress between edge and screw dislocations and their solute atmospheres formed for various waiting times with different solute content and for a range of temperatures. A simple phenomenological model is also proposed that describes the observed behavior of the critical shear stress as a function of segregation level.

Phase-Field Modeling of Chemoelastic Binodal/Spinodal Relations and Solute Segregation to Defects in Binary Alloys

“…In contrast to (linear elastic) continuum dislocation theory, non-linear effects accounted for in MPFCM result in a non-zero hydrostatic stress field in screw cores driving segregation to these as well. Note that atomistic modeling based on hybrid Monte Carlo molecular dynamics (Sadigh et al [ 16 ]), or on diffusive molecular dynamics (e.g., Dontsova et al [ 32 ], Ponga and Sun [ 33 ]), also predict segregation to screw dislocations. Again, this is in contrast to continuum modeling based on linear elasticity.…”

Kinetics of interstitial segregation in Cottrell atmospheres and grain boundaries

“…One can clearly see from Figure 1 that the approximation by Equations (19) and (20) is sufficiently accurate. It should be mentioned that a most recently performed simulation by Dontsova et al [34] with the "diffusive molecular dynamics" method has led to a time dependence very similar to Equation (20) and the diagrams in Figure 1. (18) is printed in solid line, the approximate solution (Equations (19) and (20)) in dashed-dotted line and the fit to Cottrell theory in dashed line.…”

Precipitation kinetics in metallic alloys: Experiments and modeling

“…The crystal defects interact not only with precipitates, but also with solutes. Prior to nucleation of the precipitates, there is usually a tendency for solute segregation at the crystal defect [217]. This solute segregation changes the solute distribution and thus influences nucleation [218][219][220].…”