Plastic incompatibility stresses arising from slip and twinning in extruded AZ31 magnesium alloy: in-situ synchrotron diffraction analysis using self-consistent modelling - research data

A comprehensive investigation of the evolution of internal stresses in an extruded AZ31 magnesium alloy was carried out using energy-dispersive synchrotron X-ray diffraction (ED-XRD). The study quantifies both macroscopic (first-order) and intergranular (second-order) stresses developing during uniaxial tensile deformation of the strongly fibre textured hexagonal close-packed (hcp) material. Lattice strains were measured in 16 sample orientations using nine crystallographic reflections.
An advanced q-parameter method was employed to decouple the elastic lattice strain components associated with the applied macroscopic load from those arising from grain-scale plastic incompatibilities induced by heterogeneous deformation. The results reveal pronounced plastic anisotropy, early yielding of favourably oriented grains, and substantial development of intergranular stresses resulting from heterogeneous slip activity and twinning. Slip systems were grouped according to their similarity in terms of their influence on plastic deformation and grain stresses, allowing a reduction in the number of parameters required to describe the deformation mechanisms. Furthermore, correlation of Schmid factor analysis with stress distribution functions enabled the identification of the slip and twinning systems primarily responsible for the generation of second-order plastic incompatibility stresses.