Strength and plastic deformation of polycrystalline diamond composites

ABSTRACT

The use of nanopolycrystalline diamond has allowed a systematic study on deformation of polycrystalline diamond composites (PCDCs). Bulk PCDCs samples containing either Co or SiC as a binding agent were deformed under high pressure and temperature to strains up to 18% at strain rates ∼10⁻⁵ s⁻¹. All samples exhibit strong work hardening. The strength of PCDCs depends on the amount and type of binding agents and is consistently weaker than that of diamond single crystals. The weakening may be due to the binder materials, which play an important role in affecting grain boundary structures. In SiC-based PCDC, significant grain fragmentation occurs. Nearly all grain boundaries are wetted by SiC after large deformation, resulting in lower strength. In Co-based PCDC, the microstructure is dominated by dislocations, deformation twins, and separated grain boundaries. The density of deformation twins increases significantly with strain, with the twin domain width reaching as low as 10–20 nm at 14% strain.

KEYWORDS:

• Diamond strength
• diamond plastic deformation
• polycrystalline diamond
• diamond deformation mechanism

Acknowledgements

The authors are very grateful to the PRIUS program, which provided the NPD deformation pistons, without which this project would not have been possible. Y. W. and N. N. conceived the idea of the project. Y. W., N. N., F. S., T. Y., J. G., and T. O. conducted the experiments. T. S. and T. I. synthesized and prepared the NPD samples and deformation pistons used in the experiments. H. O. conducted TEM analysis. Y. W. wrote the manuscript and all authors provided inputs and discussions.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported in part by US NSF [grant numbers EAR-1361278 and 1661489 (to Y. W.)]. Major portions of the work was performed at GeoSoilEnviroCARS (The University of Chicago, Sector 13), Advanced Photon Source (APS), Argonne National Laboratory. GeoSoilEnviroCARS was supported by the National Science Foundation – Division of Earth Sciences [grant number EAR-1634415] and Department of Energy-Geosciences [grant number DE-FG02-94ER14466]. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. The TEM work carried out at the Center for Nanoscale Materials was supported by DOE Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.