Investigations of the damage structure near the crack tip in Al-alloys by means of small angle x-ray scattering

Structural materials, such as bainitic and austenitic steels and aluminium alloys as
used in the nuclear and aircraft industry are subject to external stresses in different environments. Understanding the growth of an assumed preexisting crack under these conditions is of prime importance to prevent extensive crack propagation and failure of the component. The ongoing research aims to investigate the early stages of ductile fracture, the nucleation, growth and coalescence of microvoids and the evolution of the spatial dislocation distribution. Two commercial Al-alloys, alloys 2024-T351 and 6013-T6 used in the aircraft industry were investigated. Within the above framework, a small region around the crack tip of a 2024-T351 specimen was scanned using a microfocused beam of 5 µm in diameter (Esrf, ID13-Microfocus).
The major improvement lies in the strongly diminsihed influence of grain boundary scattering. Information from fracture toughness tests, from the simulation of the distribution of stresses and strains by means of finite element analysis, from scanning and transmission electron microscopy and positron annihilation microprobe experiments, will support the small angle X-ray scattering investigations.