Investigation of the Microstructure Evolution and Deformation Mechanisms of a Mg-Zn-Zr-RE Twin-Roll-Cast Magnesium Sheet by In-Situ Experimental Techniques.

Kristián Máthis,Heeman Choe,Klaudia Horváth,Kwang Shin,Alexei Vinogradov,Gergely Farkas

doi:10.3390/ma11020200

Abstract

Twin roll casting (TRC), with a relatively fast solidification rate, is an excellent production method with promising potential for producing wrought semi or final Mg alloy products that can often suffer from poor formability. We investigate in this study the effect of the TRC method and the subsequent heat treatment on the microstructure and deformation mechanisms in Mg-Zn-Zr-Nd alloy deformed at room temperature using the in-situ neutron diffraction and acoustic emission techniques and ex-situ texture measurement and microscopy, respectively. Although a higher work hardening is observed in the rolling direction due to the more intensive <a>-type dislocation activity, the difference in the mechanical properties of the specimens deformed in the RD and TD directions is small in the as-rolled condition. An additional heat treatment results in recrystallization and significant anisotropy in the deformation. Due to the easier activation of the extension twinning in the TD given by texture, the yield stress in the TD is approximately 40% lower than that in the RD.

Highlights

Nowadays, achieving fuel saving through weight reduction of vehicles is a key task in the transportation industry
We investigate the impact of the twin roll casting process and the subsequent heat treatment on the microstructure and the deformation mechanisms in ZEK100 magnesium alloys deformed at room temperature using Neutron Diffraction (ND) and acoustic emission (AE) technique
The combination of in‐situ neutron diffraction and acoustic emission techniques with ex‐situ texture measurement and microscopy obtained a complex characterization of the microstructural evolution and deformation mechanisms in twin roll cast Mg‐Zn‐Zr‐Nd magnesium alloy

Summary

Introduction

Nowadays, achieving fuel saving through weight reduction of vehicles is a key task in the transportation industry. Magnesium alloys, being among the lightest structural materials exhibiting an outstanding specific strength, receive a great deal of attention. Magnesium, owing to its hexagonal closed packed structure (hcp), exhibits a low strength and ductility at ambient temperatures. Various alloying elements, including zinc (Zn), zirconium (Zr) and/or different rare earth (RE) elements, are added for enhancing the mechanical performance [1]. The formability of magnesium alloys can be improved through microstructural modifications of the material by deformation processing, e.g., extrusion or rolling, at elevated temperatures stimulating activation of non-basal slips and the occurrence of dynamic recrystallization.

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Conclusion