A study of stress relaxation in AZ31 using high-energy X-ray diffraction

The micro-plasticity of the Mg alloy AZ31 is explored through high-energy X-ray diffraction (HEXD). Through cyclic loading of the sample, a softening response is found to follow the resolved shear stress for basal slip. Stress relaxation is studied by applying an incremental elongation increase while continuously collecting images from a detector array. The rate exponent associated with a particular reflection is developed by evaluating the average lattice strain in the loading direction from the composite detector image collected at a particular point in time, and then following the time evolution. A distinct rate exponent is identified for grain orientations that have a propensity for slip on second-order pyramidal planes, highlighting the capability to capture the simultaneous action of different deformation mechanisms through HEXD.