Recent research in the field of nanostructured ceramic materials has underscored the importance of using feedstock powders with metastable phases. During material consolidation the metastable structure evolves into a dual structure where the grain growth stops when the crystallites reach their respective equilibrium grain size. The mutual suppression of the grain growth is a direct consequence of the immiscibility of the two phases in the solid state. Due to their small grain size and uniform structure, these nanocomposites exhibit very interesting properties such as higher hardness and toughness.
Metastable structures can be produced using Atmospheric Plasma Spray (APS) technique from commercially available micron-sized feedstock powders. The starting immiscible phases become molten  and are homogenized during their short residence in the hot zone of the plasma jet. Afterwards, the molten droplets accelerated by the plasma jet are quenched in a liquid medium, such as water, or onto a nitrogen chilled substrate forming metastable phases.
The main target of this work has been the synthesis of metastable ceramic powders through atmospheric plasma spraying  (APS) and quenching route. The viability for producing these metastable phases and the structural characterization have been carried out.