Micron diamond composites with nanocrystalline silicon carbide bonding
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T.W. Zerda Texas Christian University, Physics and Astronomy Department, Fort Worth, Texas 76129
D. He, L. Daemen, and Y. Zhao Manuel Lujan, Jr., Neutron Scattering Center, MS-H805, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (Received 22 November 2002; accepted 12 February 2003)
Diamond composites with nanocrystalline cubic silicon carbide bonding were sintered from diamond/amorphous silicon mixtures under high pressure and high temperature (p ⳱ 5 GPa and temperatures up to 1673 K). Differential scanning calorimetry, ex situ x-ray, and Raman spectroscopy investigations showed that amorphous silicon partially transformed into nanocrystalline silicon at 873 K under 5 GPa. This was followed by the formation of nanocrystalline silicon carbide from the reaction between the silicon and diamond after silicon melting. Refinement of the x-ray diffraction patterns of composites with the Rietveld method revealed that considerable microstrain (0.3–0.5%) remained within the nanocrystalline silicon carbide grains. Small strain (0.1–0.2%) was observed in the compacted diamonds, but after the reaction they became almost strain free (
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