Thermodynamics of Interfaces: Theory to Atomistic Modeling

George Mason University, Fairfax VA

Investigators

Abstract

NONTECHNICAL SUMMARY This award supports theoretical and computational research and education on the properties of materials interfaces. Interfaces are ubiquitous and important in many natural phenomena, e.g. in how materials break and deform, and consequently play important roles in many areas of science and technology. The goal of this project is to advance fundamental understanding of the effects of temperature, chemical composition, interface shape and other factors on interface properties. The main approach to achieving this goal is close integration of general theoretical analysis with computer simulations. The research will provide a theoretical framework for the development of new models for interface properties and interface-controlled processes, and will provide new capabilities for their computational prediction. This improved understanding will enhance our ability to control materials properties for many classes of technologically important materials, including many varieties of alloys and nanowires. Furthermore, it will strengthen the theoretical foundations for the design of new nanostructured materials. The project is expected to have impact on several areas of materials science, physics, chemistry, and biology. The PI will incorporate some of the research results into courses and student projects at George Mason University, and in presentations given to students of local high-schools as part of his outreach efforts. TECHNICAL SUMMARY This award supports theoretical and computational research and education on the thermodynamic properties of materials interfaces. Interfaces are ubiquitous and important in many natural phenomena, such as materials fracture and deformation, and consequently play important roles in many areas of science and technology. The goal of this project is to advance the fundamental understanding of interface thermodynamics and investigate the effects of temperature, chemical composition, interface curvature and other factors on interface properties. Four research directions will be pursued in this project: (1) investigation of structural phase transformations in metallic grain boundaries (GBs), including the construction of GB phase diagrams; (2) investigation of structure and properties of alloy GBs at high temperatures approaching the melting point; (3) analysis of equilibrium thermal fluctuations of interface properties and development of efficient methods for computational prediction of such properties; and (4) development of thermodynamics of strongly curved interfaces, including extensions of the existing theory to non-spherical interfaces and incorporation of quadratic and higher-order effects in curvature. The atomistic simulations will utilize molecular dynamics, Monte Carlo, and other techniques. The research will provide a theoretical framework for the development of new models of phase and interface stability, phase nucleation, and other interface-controlled processes. The project will lead to a better fundamental understanding of interface thermodynamics and will provide new capabilities for its computational prediction. The improved understanding of interface thermodynamics will enhance our ability to control precipitation and coarsening in structural materials such as superalloys, solidification microstructures in cast alloys, nanowire growth, and reactive wetting. The project is expected to have impact on several areas of materials science, physics, chemistry, and biology. The PI will incorporate some of the research results into courses and student projects at George Mason University, and in presentations given to students of local high-schools as part of his outreach efforts.