From atomistics to macro-behavior: structural superplasticity in micro- and nano-crystalline materials

Abstract

Over a period of time, what started off as a phenomenological analysis for structural superplasticity in micro-grained materials has been developed into a mechanistic model and later extended to explain the quasi-viscous deformation of nanostructured materials. Regardless of the number of grain sizes, temperatures and stresses employed in the stress–grain size–temperature–strain rate space, it is now possible to account for the viscous deformation of structural superplastics and nanostructured materials in the optimal range (defined as the range from the slowest strain rate to the point of inflection on the sigmoidal log stress – log strain rate iso-thermal, iso-structural plot) with the help of 5 empirical constants. Of these, four constants can be calculated, in principle, ab initio.