Experimental study of plastic deformation during sintering of cubic boron nitride compacts

In this work polycrystalline cubic boron nitride compacts (PcBN), prepared with and without binder, were sintered at 8 GPa and 1850 degrees C using di fferent processing times. X-ray diffraction and Raman spectroscopy were use d to investigate the kinetics of plastic deformation during sintering. For compacts sintered in short processing times, both Raman and X-ray diffracti on linewidths increased, indicating a high plastic deformation of the grain s. For longer processing times (30-120 s) the linewidth decreased, tending to the value of the pristine cBN grains. This dependence on the processing time was interpreted as a result of the competition between the plastic def ormation of the grains, dominant for short processing times, and the defect annealing process, which becomes significant for longer processing times. When aluminum binder was used for sintering, it was observed that the proce ssing time required to recover the original linewidth is longer, and the ma ximum broadening of the lines occurs at a longer processing time compared t o the case without binder. These results indicated that the binder phase si gnificantly affects both plastic deformation and defect annealing processes . (C) 1999 Elsevier Science S.A. All rights reserved.