Simulation and Theory of Solid-Liquid Interfaces and Grain Boundaries

University Of Kansas Center For Research Inc, Lawrence KS

Investigators

Abstract

Brian Laird of the University of Kansas is supported by an award from the Theory, Models and Computational Methods program. The project focuses on understanding the role that atomic and molecular interactions play in shaping thermodynamic and kinetic properties of solid-liquid and solid-solid interfaces. This effort requires development, evaluation and application of new computational methods. The proposed methodology is a mixture of fundamental studies of interfaces using model potentials with studies of realistic materials. Reliable experimental results of interfacial phenomena are challenging and rare. Thus, atomistic simulation is an important means for determining the thermodynamic phenomenology of such processes. The thermodynamics and growth kinetics of interfaces in condensed matter systems are primarily controlled by two quantities: the interfacial free energy and the kinetic coefficient. The interfacial free energy between two coexisting phases is the amount of work required to reversibly form a unit area of interface. The kinetic coefficient is the constant of proportionality between the growth velocity of an advancing interface and the undercooling drop in temperature. Accurate values of both are necessary for the full understanding of phenomena such as dendritic crystal growth, crystal nucleation, wetting, liquid-metal embrittlement, and others. Specific tasks that will be addressed are: (i) new method to quantify the dependence of the interfacial free energy on atomic and molecular interactions, (ii) direct method development to calculate grain boundary free energies, (iii) method adaptation to study the interface thermodynamics and structure of chemically heterogeneous solid-liquid interfaces; (iv) method for detecting the dependence of the kinetic coefficient on intermolecular forces, and (v) method to calculate the interfacial free energy of molecular systems, including binary mixtures. Broader impacts include continued participation in a cooperative research team on Dynamics and Cohesion of Materials Interfaces encompassing semiannual collaborative meetings between materials scientists, chemists and physicists. Efforts for training of students in the techniques of computational chemistry, programming and modeling will be undertaken within the Chemistry NSF-funded REU program at Kansas University, which has a strong history of participation by underrepresented groups.