Spark plasma sintering (SPS) is a relatively new sintering-based technique [17] in which the powder to be consolidated is loaded into an electrically and thermally conductive graphite mould and a large DC pulsed current (1000–5000A) is applied under a uniaxial pressure. When current passes through the graphite mould (and the powder if it is electrically conductive), the powder is heated both from the outside (the mould acts as a heating element) and inside (due to Joule heating from the intrinsic electrical resistance of the powder material). SPS is characterised by very fast heating (up to 2000°C/min) and cooling rates and short holding times (minutes) to achieve near theoretical density [17]. Thus SPS occupies a very different time–temperature–density space in powder consolidation maps when compared with conventional methods, such as hot pressing sintering and HIP with ramp rate of 50–80°C/min and a few hours holding time. Although SPS has been studied for a rapidly growing number of materials [17], there are only a small number of studies on the fabrication and microstructural characterisation of ODS steels processed by SPS, briefly reviewed below.
