Structure and mechanical properties of TiB2/TiC - Ni composites fabricated by pulse plasma sintering method

TiB2/TiC - Ni composites were synthesized starting from the powders of Ti, B4C and Ni, using Pulse Plasma Sintering (PPS) method. Typically used one-step (1100 degrees C-10 min.) and novel double-step sintering processes (900 degrees C-10 min. +1100 degrees C-5 min.) were applied and compared. XRD studies showed that the composite obtained by double-step sintering consisted of TiB2, TiC and Ni phases. For one-step processing additionally undesired Ni3B and graphite were detected. SEM observations revealed dark-grey grains of TiB2, light-grey grains of TiC (both around 25 mu m in size) and Ni areas surrounded by TiC. The composites synthesized in one- and double-step processes revealed the hardness and relative density of 2335 HV5 (+/- 110) and 97.8% and 2470 HV5 (+/- 70) and 99.8%, respectively. Novel double-step sintering process allowed to avoid undesired phases (graphite, Ni3B) and only TiB2, TiC and Ni were present in the structure. Additionally it was possible to decrease the temperature of the process comparing to other fabrication methods. (C) 2018 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.