Structural Phase Transformations in Nanoscale Systems

Wilde G.

Abstract

As characteristic size scales of materials systems tend to progressively become shorter, size-dependent materials’ behavior becomes increasingly important. Related to many aspects concerning stability, function, and performance are phase transformations that might be necessary to obtain a specific state or are necessary to avoid to retain a specific phase or state with desired properties. At dimensions in the range of tens nanometers or below, size effects affect structural phase transformations significantly. Opinions and models about the origin of the size-dependence abound since several decades. However, more recent results allow analyzing the local atomic structure of the particle/matrix interfaces as well as local strain contributions in detail. In addition, size-dependent measurements of excess thermodynamic potentials can be carried out and rate-dependent analyses explore new regimes at significantly enhanced heating rates. These recent results serve to estimate the relative importance of kinetic and different thermodynamic contributions. Herein, the emphasis is on summarizing the recent progress that is made on the size effect and on the impact of the interfacial structure on the melting transformation of embedded nanoparticles. At the same time, these results serve to considerably enhance the understanding of the melting process in general.