Abstract
This work investigates the interrelationship among the crystallographic texture, microstructure, and deformation mechanisms, especially dislocation slip activities, in the Mg alloys accompanying the different texture formations after thermomechanical treatments. The rare-earth (RE) elements are generally known as a tailored element to texture modifying in Mg alloys. The addition of Zn combined with the RE elements exhibits a more pronounced texture modification. The Ca is regarded as a promising element that could partially replace RE elements. It has been usually noted that various recrystallization mechanisms ascribe to the texture weakening in the Mg alloys. The various recrystallization mechanisms require nucleation with grain rotation towards random orientations, which are relevantly correlated to the deformation mechanisms. A systematic investigation is emphasized to understand the influence of alloying elements, the active dislocation slip activities, and their contribution to the microstructure on the texture development based on the fact that the texture reflects the deformation mechanisms. In this work, the Mg alloys were successfully investigated by using in-situ experiments at a synchrotron for tracking texture development and change of diffraction patterns under mechanical testing at different temperatures. The obtained results were evaluated using convolutional multiple whole profiles (CMWP) analysis and electron backscattered diffraction (EBSD) measurement in terms of texture development, dislocation slip activities, and microstructure evaluations. The mutual influences between active deformation modes and recrystallization behavior at ambient and elevated temperatures were discussed. The higher activations of non-basal and pyramidal dislocations in the Nd or Ca containing Mg alloys compared to the Mg-Zn alloy were found in the CMWP analysis. The former is enhanced by the addition of Zn combined with Nd or Ca. In-grain misorientation axes (IGMA) distributions obtained from the EBSD measurement confirms that the predominant prismatic slip contributes to the higher activations of non-basal dislocation. The texture evolution shows an obvious feature for all examined sheets, which is a broadening of the basal pole perpendicular to the loading direction and a strengthening of the 〈101ത0〉 pole at the loading direction. The Zn addition in combination with the Nd or Ca shows a pronounced evolution of texture, compared to a sole addition of Nd or Ca. The Zn addition without Nd or Ca shows a less pronounced texture development. At elevated temperatures, the enhanced activation of non-basal dislocations is observed in the ZK10 deformed at 100°C. The serrated grain boundaries and fine grains at the grain boundaries, i.e. the onset of dynamic recrystallization, are observed in the ZK10 deformed at 200°C. In contrast, the uniform deformation and the retardation of the thermally activated processes, e.g. dynamic recovery and dynamic recrystallization, are observed in the other alloys. This retardation is more pronounced with the simultaneous addition of Zn with Nd or Ca.
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