Fig. 3.

a Schematic diagram illustrating different onset temperatures of sintering of nano- and micro-sized particles [44]. Relative density of pure WC as a function of initial particle size in BTC b microsize [56] and c nanosize [57]. d Relative density of micro and nano WC versus sintering temperature, without holding time [40]. e Schematic of the sintering mechanism of nano WC on the basis of the experimental shrinkage strain rate in a non-isothermal experiment [48]. f Schematic diagrams and corresponding TEM micrographs revealing the contact state of WC and ZrC nano-particles during sintering [63].

Figure panels reproduced from Ref. [44] with permission from Taylor & Francis copyright 2008, Ref. [56] with permission from Elsevier copyright 2004, Ref. [57] with permission from Elsevier copyright 2017, Ref. [40] with permission from Elsevier copyright 2008, Ref. [48] with permission from Elsevier copyright 2011, Ref. [63] with permission from Elsevier copyright 2015