NSF-Europe: Computer-Based Discovery of Novel, Low-Temperature Structures in Intermetallic Compounds

Northern Arizona University, Flagstaff AZ

Investigators

Abstract

This NSF-Europe award supports international collaborative research on intermetallic compounds. The structure of many intermetallics is unknown experimentally. The PI will use a Mixed-Basis Cluster Expansion in conjunction with modern statistical mechanics ground state search techniques to predict stable structures for intermetallics that have so far eluded experimental determination. This will include: (a) structures of CuPd and CuMn with one- and two-dimensional periodicities, (b) ordering of vacancies in early transition metal nitrides and carbides - in these systems, the vacancies form peculiar spatial arrangements, and (c) determination of the fundamental phase behavior of Mo-Ta and Nb-W. The study of these material systems also requires development of new methodologies: 1. Development of new kinetic-Monte Carlo codes to study evolution of microstructures. 2. Development of a "genetic algorithm" approach to determining ground states in alloy systems. 3. Development of mixed-basis cluster expansion codes that handle BCC-based alloys. The broader impacts of the project include: potential for advances in understanding technologically important materials; developing tools for studying alloys that will be freely available to other researchers; and providing undergraduate students, especially those from under-represented groups in physics and materials science, with research experience, training in computation, and one-to-one faculty mentoring. The proposed collaboration involves a group in Erlangen Germany, particularly noted for its interest in low-dimensional aspects of materials. This NSF project is co-funded by the Office of Multidisciplinary Activities, the Division of Materials Research, and the International Office (Western Europe) as a Cooperative Activity in Materials Research between the NSF and Europe (NSF 02-135). %%% This NSF-Europe award supports international collaborative research on intermetallic compounds. Crystal structure determines properties such as ductility, hardness, and conductivity. Yet the structure of many intermetallics is unknown experimentally. The PI will use a first principles methodology for predicting stable crystal structures to study different intermetallic compounds at non-ideal stoichiometries. The PI will also development additional methodologies and codes to facilitate study such systems. The broader impacts of the project include: potential for advances in understanding technologically important materials; developing tools for studying alloys that will be freely available to other researchers; and providing undergraduate students, especially those from under-represented groups in physics and materials science, with research experience, training in computation, and one-to-one faculty mentoring. The proposed collaboration involves a group in Erlangen Germany, particularly noted for its interest in low-dimensional aspects of materials. This NSF project is co-funded by the Office of Multidisciplinary Activities, the Division of Materials Research, and the International Office (Western Europe) as a Cooperative Activity in Materials Research between the NSF and Europe (NSF 02-135). This project is being carried out in collaboration with the Universitat Erlangen-Numberg in Erlangen, Germany. ***