Prof Jeffrey Hoyt - McMaster University, Canada
Professor J.J. Hoyt received his BS degree in Materials Science and Engineering from Cornell University and his MS (1982) and PhD (1986) in Physical Metallurgy from the University of California, Berkeley. From 1988 to 1996 Dr. Hoyt was a faculty member in the department of Mechanical and Materials Engineering at Washington State University, achieving the rank of associate professor. From 1997-2007 Prof. Hoyt was a senior member of the technical staff at the Sandia National Laboratories at both the Livermore, CA and Albuquerque, NM sites. Prof. joined the department of Materials Science and Engineering at McMaster University in 2007 and in 2012 was named chair of the department.
Prof. Hoyt is the author or co-author of over 100 papers in refereed scientific journals and has presented over 50 invited presentations at national and international scientific conferences. His research expertise is the study of phase transformations in materials using advanced computational tools such as molecular dynamics and Monte Carlo simulations.
What can we learn about solidification from atomistic simulations?
J. J. Hoyt
Dept. of Materials Science and Engineering, McMaster University, Canada
The microstructure and composition profile in a solidified component depend to a large extent on the kinetic and thermodynamic properties of the solid-liquid interface, but experiments to characterize the interface are often difficult to perform. In this lecture we will review various molecular dynamic and Monte Carlo simulation techniques that have been developed over the past several years to provide insights into the interface properties. First, the capillary fluctuation method will be reviewed and it will be shown that the method is capable of providing an accurate determination of the solid-liquid interfacial energy and its small anisotropy, the latter property being critical to the growth kinetics and morphology of dendrites. Second, several molecular dynamics methods for extracting the kinetic coefficient of a rough interface will be described. In addition, it will be shown how the techniques can be extended to model the kinetic coefficient of steps on a facetted solid-liquid boundary. Third, the application of molecular dynamics to the study of solute trapping during rapid solidification will be described. A comparison of simulation results for the Cu-Ni system will be compared with the leading theoretical descriptions of solute trapping. Finally, it will be demonstrated how atomistic simulations can be used to determine the cavitation pressure of a liquid metal or alloy. The negative pressure at which a liquid can spontaneously nucleate a void is an important parameter in models describing a casting defect known as hot tearing. In particular, results for Al will be presented, where a large discrepancy between simulation and experiments is found, and reasons for the disagreement will be discussed.