Review of thermo-kinetic correlation during grain growth in nanocrystalline materials

Nanocrystalline (NC) materials exhibit many unique properties over their coarse-grained counterparts due to the high grain boundary density and the small grain size, but they are too difficult to be used in engineering environment because of the poor thermal stability. With regard of this, two strategies are previously proposed to enhance the thermal stability (or impede the grain growth) of NC materials, that is, the thermodynamic and the kinetic approaches. Recent investigations increasingly support that the two approaches may be physically interacted and acted on each other, and they can be treated together within a unified thermo-kinetic framework. This paper reviews the progress in the investigation of thermo-kinetic correlation during grain growth in NC materials. First, the theoretical models to describe the concept of the thermo-kinetic correlation and the grain growth equations developed based on the thermo-kinetic correlation are reviewed. Second, experimental and simulated evidences to support the coexistence of thermodynamic and kinetic effects are summarized. Third, the potential application of thermo-kinetic correlation is analyzed and discussed. This paper shows that the stabilization of NC materials can be tailored by the selection of the suitable strategies. Finally, several directions that require further exploration are identified.