Hardness and fracture toughness of brittle materials: A density functional theory study

Zenong Ding, Shujia Zhou, and Yusheng Zhao
Phys. Rev. B 70, 184117 – Published 18 November 2004

Abstract

The focus of the paper is to study the correlation between hardness and fracture toughness of brittle materials. To this end, density functional theory (DFT) is used to calculate materials parameters such as the surface energies, the unstable stacking fault energies, the Young’s modulus, the bulk modulus, the shear moduli, and the Poisson’s ratio of crystalline B6O as well as the surface energies of cBN and 3CSiC. With these calculated materials parameters as well as reported ones, the theoretical fracture toughness of diamond, cBN, B6O, 3CSiC, and Si are obtained and compared with experimental hardness. We find that the theoretical fracture toughness, proportional to the product of shear modulus and surface energy, can better characterize hardness of diamond, cBN, B6O, 3CSiC, Si, and possibly other brittle materials than shear modulus alone [D. M. Teter, MRS Bull. 23, 22 (1998)]. This finding could be helpful in searching for new hard materials.

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  • Received 22 December 2003

DOI:https://doi.org/10.1103/PhysRevB.70.184117

©2004 American Physical Society

Authors & Affiliations

Zenong Ding1, Shujia Zhou2,*, and Yusheng Zhao3

  • 1Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA
  • 2Department of Mechanical Engineering, The Johns Hopkins University, Baltimore, Maryland 21218, USA
  • 3Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA

  • *Email address: szhou@pegasus.me.jhu.edu

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Issue

Vol. 70, Iss. 18 — 1 November 2004

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