Mechanical Instability and Ideal Shear Strength of Transition Metal Carbides and Nitrides

Seung-Hoon Jhi; Steven G. Louie; Marvin L. Cohen; J. W. Morris, Jr

doi:10.1103/PhysRevLett.87.075503

Mechanical Instability and Ideal Shear Strength of Transition Metal Carbides and Nitrides

Seung-Hoon Jhi, Steven G. Louie, Marvin L. Cohen, and J. W. Morris, Jr.

Phys. Rev. Lett. 87, 075503 – Published 27 July 2001

Abstract

The ideal shear strength of transition metal carbides and nitrides is calculated with the use of the ab initio pseudopotential density functional method. The microscopic mechanism that limits the ideal strength is studied using full atomic and structural relaxation and the results of electronic structure calculations. It is shown that plasticity in perfect crystals can be triggered by electronic instabilities at finite strains. Our study explicitly demonstrates that the ideal strength in these materials is limited by the elastic instability which is in turn initiated by electronic instabilities. The potential application of alloy hardening due to the onset of instabilities at different strains is also discussed.

Received 9 March 2001

DOI:https://doi.org/10.1103/PhysRevLett.87.075503

Authors & Affiliations

Seung-Hoon Jhi^1,3, Steven G. Louie^1,3, Marvin L. Cohen^1,3, and J. W. Morris, Jr.^2,3

¹Department of Physics, University of California at Berkeley, Berkeley, California 94720
²Department of Materials Science and Mineral Engineering, University of California at Berkeley, Berkeley, California 94720
³Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720