Acta Materialia 50 (2002) 619–631 www.elsevier.com/locate/actamat First-principles study of metal–carbide/nitride adhesion: Al/VC vs. Al/VN Donald J. Siegel a,* , Louis G. Hector Jr. b,1 , James B. Adams c,2 a Department of Physics, University of Illinois at Urbana–Champaign, 1110 West Green Street, Urbana, IL 61801, USA b Surface Science Division, ALCOA Technical Center, ALCOA Center, PA 15069-0001, USA c Chemical and Materials Enigneering Department, Arizona State University, Tempe, AZ 85287-6006, USA Received 7 August 2001; accepted 31 August 2001 Abstract We have performed density functional calculations to investigate the adhesion and electronic structure at interfaces between Al and the refractory transition metal nitrides/carbides VN and VC in order to understand the significance of the ceramic’s metalloid component upon interfacial properties. We find that for both systems the preferred bonding site places the metal interfacial atoms above the ceramic’s metalloid atoms, and that adhesion energies are comparable to those found for other metals (Ti, Ag) on MgO. The differences in magnitude and rank-ordering of the adhesion energies for the two interfaces are rationalized in terms of the the surface energies of the ceramics. Analysis of the charge density and density of states reveals that covalent Al–C/N bonds constitute the dominant metal–ceramic interac- tion.  2002 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved. Keywords: Ab initio calculation; Aluminum; Carbides; Interfacial adhesion; Nitrides 1. Introduction Interfaces between metals and ceramics play a vital role in many industrial applications [1]: het- erogeneous catalysis, microelectronics, thermal barriers, corrosion protection and metals pro- * Corresponding author. Present address: Thin Film and Interface Science Group, Sandia National Laboratories, Mail Stop 9161, Livermore, CA 94551-0969, USA. Tel.: 925-294- 3089; fax: 925-294-3231. E-mail address: djsiege@sandia.gov (D.J. Siegel). 1 Present address: General Motors R&D Center , Mail Code 480-106-224, 30500 Mound Rd, Warren, MI 48090-9055, USA. 2 Visit http://ceaspub.eas.asu.edu/cms. 1359-6454/02/$22.00  2002 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved. PII:S1359-6454(01)00361-5 cessing are but a few representative examples. However, experimental complications associated with the study of a buried interface, and theoretical difficulties arising from complex interfacial bond- ing interactions, have hindered the development of general, analytic models capable of accurately pre- dicting fundamental interfacial quantities. One such quantity that is key to predicting the mechanical properties of an interface is the ideal work of adhesion, W ad [1], which is defined as the bond energy needed (per unit area) to reversibly separate an interface into two free surfaces, neg- lecting plastic and diffusional degrees of freedom. For example, the degree of plastic deformation that occurs during interfacial fracture is known to