Overview

Fatigue crack growth is a process that is described macroscopically by quantities such as the stress intensity factor, J-integral or plastic part of the J-integral. There are many models of crack propagation at the microscopic level that consider plastic deformation around the crack tip, but which differ in details. Advances in experimental methods allow more accurate and detailed experimental study of these processes and, consequently, their more accurate description and modelling using advanced molecular statics and dynamics methods.

The aim of this work will be to collect as much details as possible about the processes at the tip of a fatigue crack during its growth, both on the surface of the specimens and in their volume. Modern methods will be used: high-resolution digital image correlation (HR DIC), electron channelling contrast imaging (ECCI), high-resolution electron backscatter diffraction (HR EBSD), focused ion beam (FIB) to observe the processes on selected sections and to prepare TEM lamellae. The observations will be complemented by simulation of microscopic processes using molecular dynamics or discrete dislocation dynamics.

The measurement methods will first be validated on pure copper as a model material and then applied to oxide dispersion strengthened (ODS) materials prepared by additive technologies.