Effects of bimodal basal texture on bending stress and microstructure evolution of Mg-2.6Nd-0.55Zn-0.5Zr alloys
(School of Materials Science and Engineering, Harbin Institute of Technology at Weihai, Weihai 264209, China)
Abstract: The extrusion direction (ED) and transverse direction (TD) samples were cut from Mg-2.6Nd- 0.55Zn-0.5Zr alloy sheet, and the effects of bimodal basal texture on the bending stress and microstructure evolution were investigated. Results showed that the ED sample with weak basal texture possessed much lower bending stress than the TD sample. This anisotropy is attributed to the role of different textures on the evolution of deformation mechanisms and microstructures. For the ED sample with weak basal texture, the dominant deformation mechanisms were basal slip in the majority with minor supplement of tension twin in the inner region while basal slip and prismatic slip in the outer region. In comparison, the TD sample with strong basal texture activated more tension twin in the inner region and more prismatic slip in the outer region. The activation of tension twin promoted the development of á0002？//compression direction type texture with the confined ±30° angle range in the inner region and reduced the emergence propensity of high dislocation density and low angle grain boundaries. The massive activation of tension twin allowed the TD sample to maintain a high strain-hardening capacity, which was the fundamental reason for the high bending stress in this sample.
Key words: Mg-Nd-Zn-Zr alloy; texture; tension twin; three-point bending; bending stress; microstructure evolution