On the Contact of Liquid Nickel with Tungsten Carbide or Boron Carbide

AbstractMetal matrix composites (MMCs), consisting of a ceramic reinforcing phase combined with a tough metal matrix can be applied to steel substrates as wear coatings. The processing behaviour of two nickel matrix MMC's is investigated: Ni-WC and Ni-B4C. Experiments were designed and carried out where WC or B4C was added to molten nickel. The temperature range was from 1773 to 1973 K, with times of contact between ceramic and nickel ranging from less than one minute to over 30 minutes. The nominal addition of WC ranged from a molar ratio (Ni:ceramic) of 4.2 to 167.0 while B4C additions varied from about 1 to 94. The melt was sampled following the addition of the ceramic. Analysis techniques included chemical analysis, optical microscopy, electron microprobe microanalysis and X-ray diffraction. In the Ni-WC system, a portion of WC reacted resulting in tungsten dissolution into the nickel. Reactions in the Ni-B4C system produced nickel borides, principally Ni3B in the form of a eutectic with nickel and pr...