Summary: Stoichiometry and Adhesion of Al/WC
Donald J. Siegel
Department of Physics, University of Illinois at Urbana-Champaign,
1110 West Green St., Urbana, IL, 61801.
Louis G. Hector, Jr.
GM Research and Development Center,
30500 Mound Road, P.O. Box 9055, Warren, MI 48090
James B. Adams
Chemical and Materials Engineering Department,
Arizona State University, Tempe, AZ 85287-6006.
We examine the relative stability and adhesion of nonstoichiometric (polar) Al/WC interfaces and
WC(0001) surfaces using Density Functional Theory as implemented in a planewave, pseudopo-
tential formalism. Relaxed atomic geometries and the ideal work of adhesion were calculated for
six different interfacial structures, taking into account both W- and C-terminations of the carbide.
Based on the surface and interfacial free energies, we find that both the clean surface and the op-
timal interface geometry are W-terminated. However, the largest adhesion energies are obtained
with the C-termination, consistent with an argument based on surface reactivity.
Interfaces between metals and ceramics play a vital role in an increasingly large number of indus-