On the Experimental Assessment of Thermodynamic Stability of Nanostructured Solid Solutions

Thermal stability in nanocrystalline alloys has been extensively explored using both experimental and theoretical approaches. However, there is rarely any direct evidence of the specific stabilization mechanisms. Therefore, whether the stability is achieved by kinetic barriers or by reaching an equilibrium thermodynamic state remains an open question. Indeed, although kinetic and thermodynamic stabilities are intrinsically different from the conceptual point of view, their experimental assessment, identification, and results interpretation present several difficulties. In this regard, a general agreement about the experimental findings required to ascertain the thermodynamic stability is also still missing. In this work, a thorough discussion on the experimental assessment of thermodynamic stability of nanostructured solid solutions is presented and experimental conditions sine qua non able to, at least, identify the possibility of thermodynamic stability occurrence is proposed.