Grain-size effect on the deformation of Mg–3Al–3Sn alloy: Experiments and elastic-viscoplastic self-consistent modeling. (August 2021)

• Record Type: Journal Article
• Authors: Zhu, Gaoming; Wang, Leyun; Sun, Yingjun; Shang, Xiaoqing; Wang, Jie; Wang, Huamiao; Zeng, Xiaoqin
• Is Part Of: International journal of plasticity. Volume 143(2021)
• Publication Date: 2021-08
• Subjects: Crystal plasticity -- Polycrystalline material -- Microstructures -- Electron microscopy -- EVPSC; Plasticity -- Periodicals; Plasticité -- Périodiques; Plasticity; Periodicals; 620.11233
• DOI: 10.1016/j.ijplas.2021.103018
• Languages: English
• ISSNs: 0749-6419

Abstract

Abstract: Grain refinement can significantly change the tensile behavior of Mg alloys. The underlying mechanisms are unclear yet. Here we report that grain refinement of a Mg–3Al–3Sn (wt.%, AT33) alloy increases the yield strength ( σ 0.2 ) following the Hall-Petch law, while decreases the strain hardening exponent ( h ). Tensile stress-strain curves and lattice strain evolution of four rolled AT33 samples with different grains sizes (10–97 μm) can be simulated by an elastic-viscoplastic self-consistent (EVPSC) model that takes grain size into account. The key to the model's success is that it allows both the initial critical resolved shear stress (CRSS) and the dislocation nucleation coefficient of different slip modes to be functions of the grain size. The coarse-grained samples have higher dislocation nucleation coefficient due to concurrently formed deformation twins. The model predicts that prismatic slip is the dominant deformation mode in this AT33 alloy; pyramidal and slips are more active in coarse-grained samples than in fine-grained samples. Highlights: Grain size effect was incorporated into the EVPSC model. The model accurately simulates the hardening of AT33 Mg alloy of 4 grain sizes. Coarse-grained material has higher dislocation nucleation rate. The model predicts more pyramidal slip in coarse-grained samples.