Texture Evaluation of a Bi-Modal Structure During Static Recrystallization of Hot-Deformed Mg-Al-Sn Alloy
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NOW-A-DAYS, the increasing demands of lightweight and fuel-efficient vehicles make magnesium more preferable for such applications. Magnesium has the lowest density with the highest strength-to-weight ratio among all the structural metals and could provide significant weight savings in automotive structure and reduce harmful CO2 emission.[1] One of the main obstacles for using wrought Mg-alloys is the development of strong preferred crystallographic orientation (texture) which significantly limits the low-temperature formability.[2,3] In Mg-alloys, deformation is generally preferred on the basal {0002} h1120i slip system due to the lowest critical resolved shear stress. Alteration of the strong basal texture is important to improve the formability of wrought Mg-alloys, and several approaches have been considered to alter or weaken the unfavorable texture. Factors that affect the nucleation and growth during recrystallization, such as solid solutions and second-phase particle, may also affect the recrystallized texture.[4] In Mg-alloys, recrystallized texture can be modified in the presence of second-phase particles depending on the type, morphology, and distribution of the particles. Particle-stimulated nucleation (PSN) has been by far the most suitable mechanism that explains the texture weakening in Mg-alloys due to the
precipitates, although the effect of PSN on overall texture was reported to be low due to the lack of large amounts of precipitates in conventional Mg-alloys, such as AZ31.[5,6] A dispersion of closely spaced particles generally affects the recrystallization kinetics by grain boundary pinning and may also affect the final texture.[4] Annealing after deformation has also been reported to weaken the recrystallized texture. Huang et al. [7] reported the formability improvement of AZ31 alloy due to the texture weakening by rolling and annealing at high temperature. Slight weakening of initial static recrystallized texture was also reported for wrought Mg-alloys during annealing followed by the development of stronger basal texture during subsequent grain coarsening.[8,9] In conventional Mg-alloys, grain coarsening has always been reported to strengthen the basal texture, due to the growth preference of the basal grains, i.e., the grains that coarsen are mostly basal oriented.[10] Farzadfar et al.[11] reported the initial texture weakening during annealing of cold-deformed Mg-Y alloy was due to the solute drag effect of Y in the solid solution. There is no concrete study that correlates the effect of precipitates on the static recrystallized texture in Mg-alloys. Therefore, in this study, the goal is to investigate the effect of dynamic precipitates on the static recrystallized behavior of textural evolution.
II. ABU SYED HUMAUN KABIR, Postdoctoral Research Fellow, JING SU, Ph.D. Candidate, and STEPHEN YUE, Professor, are with the Department of Mining and Materials Engineering, McGill University, Montreal, QC, H3A 0C5, Canada. Contact e-mail: [email protected] Manuscript submitted January 2, 2016. ME
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