Revealing the dislocation mechanisms underlying strain path changes

Metal forming involves several subsequent deformation modes. Such strain path changes lead to a dramatic change in the mechanical properties and failure, due to reorganization of the already established microstructure of dislocations. The fundamental mechanisms underlying this process have been elusive due to lack of representative data for the microstructure dynamics. In a recent experiment at ID06, the evolution of 40,000 dislocation cells were visualised. We propose to apply same methodology, but to a sample pre-deformed in an orthogonal direction. Being able to visualise the process provides unique information on how the microstructure breaks up and reassembles. Next, to understand the underlying mechanisms we will introduce a comprehensive DFXM analysis approach that simultaneously maps the elastic strain, the geometrically necessary dislocation density and the total dislocation density. All in 3D, with 200 nm resolution as function of load after the strain path change.