REFINEMENT OF POLYCRYSTALLINE DISORDERED CUBIC SILICON-CARBIDE BY STRUCTURE MODELING AND X-RAY-DIFFRACTION SIMULATION

Disordering in SiC is analyzed both theoretically and experimentally. Classification of the stacking faults into (i) intrinsic, (ii) twin-like and (iii) extrinsic faults is proposed. This classification correlates well with distinct diffraction effects, characteristic for specific faults. Based on proposed classification, the disordering in SiC beta-powders obtained by SHS method (self-propating high-temperature synthesis) is analysed both qualitatively and quantitatively. It is shown that in the beta-powders a single cubic domain has an average size of approx. 55 Si-C double layers. Those domains separated by intrinsic faults (approximate to 80%) form several hundred layers large blocks which are separated from each other by twin-like (approximate to 5%) and/or extrinsic faults (approximate to 15% of total number of stacking faults).