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Abstract

Employing atomistic simulations to investigate structural phase transformations in solids is a challenging task. A prerequisite for analysing the simulation results is the ability to locally identify structures and structural features. It is then possible to find point and extended defects and to track e.g. the movement of an interface between two structures during a phase transformation. To address this problem we have implemented a polyhedron analysis method. Within our approach we analyse the local coordination polyhedra around each atom and establish a fingerprint that reflects the arrangements of polyhedra within the polyhedron network. The distribution of polyhedra in a structure together with the fingerprint then provides sufficient information to classify a given structure.

The polyhedron analysis method is based on the distinct geometrical features of complex phases that form in metal alloys. The formation and growth of such complex phases is of particular interest since they can significantly influence the materials properties. Insight on the atomistic level provides valuable information on the underlying microscopic processes. We have applied our polyhedron analysis in molecular dynamics and adaptive kinetic Monte Carlo simulations, to track vacancies, monitor phase growth, identify interfaces and follow their motion.