X-ray examination of the CVD BN texture evolution during phase transformations of rhombohedral modification at high pressures and temperatures

摘要

X-ray transmission photography and reflection diffractometry have been used to study the texture of phases that are formed in crystal-oriented transformations in pyrolytic BN at a pressure of 7.7 GPa and temperatures ranging from room temperature to 2000 ℃. A universal relation has been found between the scattering angle of the axial unlimited texture and azimuthal extension of the texture peaks in the X-ray pattern. Texture characteristics and mutual orientations of the phases at different stages or p, T-treatment have been defined. The use of highly textured deposits of pyrolytic BN is promising for production of crystal-oriented superhard materials and realization of martensite transformations in them to produce crystal-oriented superhard materials.