Phase composition and substructure characteristics of superhard boron nitride polycrystals sintered at different temperatures

L.I.Gladkikh, Z.I.Kolupaeva, A.V.Bochko*, N.N.Kuzin**


Kharkiv State Polytechnical University, 21 Frunze St., 310002 Kharkiv, Ukraine
*Institute for Materials Science Problems, National Academy of Sciences of Ukraine, 3 Krzhizhanovsky St., 252688 Kyiv, Ukraine
** Institute for High Pressure Physics, Russian Academy of Sciences, Troitsk, Moscow Region, Russia

Received July 16, 1998

The phase composition and substructure characteristics of superhard boron nitride polycrystals produced by sintering of the wurtzite type boron nitride at temperatures from 1670 to 1900 K have been studied by X-ray structure analysis. The sintered samples contain all three known BN modifications: wurtzite, sphalerite and graphite-like, the latter being in a stressed (compressed) state. The lattice periods, the coherently scattering domain size, concentrations of extrinsic and deformation stacking faults in the wurtzite phase have been determined as functions of the sintering temperature. The deformation stacking faults effect on the phase transformation BNwO BNsph has been revealed.

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