Improved Ductility of Boron Carbide by Microalloying with Boron Suboxide
- Creators
- Tang, Bin
- An, Qi
- Goddard, William A., III
Abstract
Boron carbide (B_4C) is the third hardest material in nature, but applications are hindered by its brittle failure under impact. We found that this brittle failure of B_4C arises from amorphous shear band formation due to deconstruction of icosahedral clusters, and on the basis of this model we suggest and validate with quantum mechanics (QM, PBE flavor of density function theory) that a laminated B_4C–B_6O composite structure will eliminate this brittle failure. Using QM to apply shear deformations along various slip systems, we find that the (001)/[100] slip system has the lowest maximum shear strength, indicating it to be the most plausible slip system. We find that this composite structure has a shear strength of 38.33 GPa, essentially the same as that of B_4C (38.97 GPa), indicating the same intrinsic hardness as B4C. However, the critical failure strain for (001)/[100] slip in the composite is 0.465, which is 41% higher than B_4C, indicating a dramatically improvement on ductility. This arises because incorporation of B_6O prevents the failure mechanism of B_4C in which the carbene formed during shear deformation reacts with the C–B–C chains. This suggests a new strategy for designing ductile superhard ceramics.
Additional Information
© 2015 American Chemical Society. ACS AuthorChoice - This is an open access article published under an ACS AuthorChoice License, which permits copying and redistribution of the article or any adaptations for non-commercial purposes. Received: August 19, 2015; Revised: October 5, 2015; Published: October 7, 2015. This work was supported by the Defense Advanced Research Projects Agency (W31P4Q-13-1-0010), by the U.S. Army Research Laboratory under Cooperative Agreement number W911NF-12-2-0022, and by the National Science Foundation (DMR-1436985). B.T. and Q.A. contributed equally to this work. The authors declare no competing financial interest.Attached Files
Published - acs_2Ejpcc_2E5b08086.pdf
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Additional details
- Eprint ID
- 61990
- DOI
- 10.1021/acs.jpcc.5b08086
- Resolver ID
- CaltechAUTHORS:20151109-102729781
- W31P4Q-13-1-0010
- Defense Advanced Research Projects Agency (DARPA)
- W911NF-12-2-0022
- Army Research Laboratory
- DMR-1436985
- NSF
- Created
-
2015-11-09Created from EPrint's datestamp field
- Updated
-
2021-11-10Created from EPrint's last_modified field
- Other Numbering System Name
- WAG
- Other Numbering System Identifier
- 1134