Tweed and Nanoscale Cubic / Tetragonal Phase Mixtures in Decomposing Alloys: the Pseudospinodal Concept
In this paper the concept of pseudospinodal decomposition introduced by Ni and Khachaturyan  as a symmetry-lifting continuous phase separation, which can produce coherent nanoscale morphologies ranging from nanowires to nanolaminates, is reviewed. The term spinodal arises from the continuous change in the compositions of emerging cubic and tetragonal phases resulting in quasi-periodic microstructures stemming from the attendant transformation strain and surface energy anisotropies. It is argued here that important features of the pseudospinodal mechanism can be understood in terms of conventional classical and non-classical nucleation and that the behaviour is more general than the cubic → tetragonal transformation context articulated by its authors. Also, the possible relevance of the pseudospinodal mechanism to studies of decomposition of hypostoichiometric Fe-Pd alloys will be presented.
Yves Bréchet, Emmanuel Clouet, Alexis Deschamps, Alphonse Finel and Frédéric Soisson
W. A. Soffa et al., "Tweed and Nanoscale Cubic / Tetragonal Phase Mixtures in Decomposing Alloys: the Pseudospinodal Concept", Solid State Phenomena, Vols. 172-174, pp. 344-349, 2011