Recrystallization mechanisms, grain refinement, and texture evolution during ECAE processing of Mg and its alloys. (November 2021)

• Record Type: Journal Article
• Authors: Kecskes, Laszlo J.; Krywopusk, Nicholas M.; Hollenweger, Yannick; Krynicki, Jenna N.; Prameela, Suhas Eswarappa; Yi, Peng; Liu, Burigede; Falk, Michael L.; Kochmann, Dennis M.; Weihs, Timothy P.
• Is Part Of: Mechanics of materials. Volume 162(2021)
• Publication Date: 2021-11
• Subjects: Magnesium -- Mg -- Mg–Al Alloys -- Mg-Zn Alloys -- Mg-Zn-Ca Alloys -- Equal-channel angular extrusion -- Grain size refinement -- Dynamic recrystallization -- Twinning -- Texture evolution; Strength of materials -- Periodicals; Mechanics, Applied -- Periodicals; Résistance des matériaux -- Périodiques; Mécanique appliquée -- Périodiques; Mechanics, Applied; Strength of materials; Periodicals; Electronic journals; 620.11
• DOI: 10.1016/j.mechmat.2021.104067
• Languages: English
• ISSNs: 0167-6636

Abstract

Abstract: This article presents key findings from a study of the microstructural evolution and grain size refinement of equal-channel angular extrusion (ECAE)-processed Mg and Mg-based alloys. Firstly, we delineate the experimental trends and material characteristics of grain size distribution and texture of as-cast pure Mg and rolled AZ31B which were processed via ECAE. We then identify and describe the primary controlling mechanisms of dynamic recrystallization (DRX) and twinning and how their interaction affects the overall refinement process. Secondly, using preliminary results from ongoing studies of other Mg-based model binary and ternary systems, with access to precipitation hardening mechanisms, we present new opportunities and beneficial outcomes that could affect and control the material's microstructural properties. Thirdly, we provide a summary of prior and concurrent modeling and simulation efforts that capture and emulate the experimentally observed trends of DRX and illustrate their predictive capability. We then, within a Materials-by-Design and Optimization framework, conclude with implications for future developments in Mg alloy research. Highlights: Key linkages between processing, microstructure, properties, and relevant characteristics for Mg and Mg alloys. Characterization of ECAE processed pure Mg and AZ31B reveal a moderate grain size refinement. Inverse pole figures show emergence of a weaker, more diffuse texture. Twin volume fraction of pure Mg vs. average grain size shows changed deformation behavior with increasing extrusion rate. Changes in internal stress and onset of DRX in pure Mg can be captured via predictive modeling.