Facilitating Basal Slip to Increase Deformation Ability in Mg-Mn-Ce Alloy by Textural Reconstruction Using Friction Stir Processing

The widespread application of wrought magnesium alloys is hampered by their insufficient formability at room temperature. The tensile ductility of a newly developed Mg-Mn-Ce alloy has been dramatically improved by friction stir processing (FSP). The microstructure of the stir zone was characterized mainly by elongated fine grains which were highly separated by low-angle grain boundaries because of the high contribution of continuous dynamic recrystallization. A new {0002} distribution with high basal plane tilt angles which facilitated 〈a〉 basal slip when the specimens were pulled along the FSP direction was obtained. Both the enhanced basal slip and crystallographic orientation evolution of Mg crystals increased the strain hardening exponent of the FSP specimen, and hence improved its tensile ductility. A material flow model, developed based on the local textural evolution, could reasonably explain the phenomenon that the FSP specimen exhibited warping and a high normal anisotropy ratio during tensile test.