Work

Solute-drag forces from short-time equilibrium fluctuations of crystalline interfaces

Year: 2025

Type: article

Abstract: The design of polycrystalline alloys hinges on a predictive understanding of the interaction between the diffusing solutes and the motion of the constituent crystalline interfaces. Existing frameworks ignore the dynamic multiplicity of and transitions between interfacial structures and phases. Here, we develop a computational framework based on short-time equilibrium fluctuations within molecular dynamics simulations to extract the average stiffness associated with the drag force exerted by the segregating solutes. We show that the random walk of a solute-loaded interface is necessarily non-classical at short timescales due to the confining solute cloud. The behavior due to the much slower stochastic evolution of the cloud can be modeled as an exponentially sub-diffusive Brownian motion in an external trapping potential. The average drag stiffness of the potential yields the net drag force. At longer timescales, the interfacial and bulk forces lead to a gradual recovery of the classical random walk of the interface with a diffusivity set by extrinsic mobility. The short timescales inherent in the response offers a viable high-throughput strategy for extracting drag stiffness and forces, enabling the rational design of alloys to control the microstructural evolution in polycrystals, and in particular, for designing stable nanocrystalline alloys.

Source: Journal of Applied Physics

DOI: 10.1063/5.0244892

Authors: Changjian Wang, Moneesh Upmanyu

Institution: Northeastern University

Language: English

Topic: Solidification and crystal growth phenomena

Subfield: Materials Chemistry

Field: Materials Science

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $3,500

Funder: Army Research Office