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Prof. Wang and his team Published Article naming “A comprehensive review of magnesium-based alloys and composites processed by cyclic extrusion compression and the related techniques” on Progress in Material Science

SEPT 9,2022   

Prof. Wang and his team from the School of Materials Science and Engineering of SJTU have published an review paper which conducts a comprehensive review of the published peer-reviewed journal articles and book chapters according to the guidelines of the Preferred Reporting Items for Systematic Reviews and meta-Analyses, providing a source of information on the application of CEC and the related techniques on magnesium-based alloys and composites.


Magnesium, its alloys and composites with an approximate density of two-thirds of aluminum and a quarter of steel are the most prominent engineering materials in various industries, with particular attention to transportation and aerospace applications due to a decrease in fuel consumption and emissions reduction. However, its relatively low mechanical properties induce significant restrictions to achieve its further advanced applications. In this regard, the severe plastic deformation approach and particularly its sophisticated technique, cyclic extrusion compression (CEC), is a promising tool to improve such shortcomings. Unfortunately, due to the hard-to-deform nature of Mg, its deformation mechanisms and the involved parameters are very complicated, necessitating a comprehensive investigation. However, there are limited encyclopedic and precise studies on the CEC-induced microstructural evolution and their mechanical properties. Therefore, this study aims to scrutinize the properties of CEC-processed magnesium alloys and composites, specifically their microstructural and mechanical properties. To this end, the corresponding deformation mechanisms and texture evolutions through the CEC-based processes are addressed based on the dislocation slip, deformation twinning, stacking fault energy, and grain boundaries in order to correlate the structure with mechanical properties, superplasticity, and biocorrosion behavior. Initially, various CEC-based techniques are systematically explained, including the reported dies and setups. Secondly, the deformation behavior of Mgbased alloys and the involved parameters are discussed. Then, the effects of the CEC process on deformation and microstructural evolutions together with grain refinement mechanisms,texture, and grain orientation behavior are explained thoroughly. Meanwhile, the other properties, including superplasticity, tribological behavior, biological and biocorrosion response, and solid-state recycling are also considered. The present article additionally deals with the simulation works related to the mentioned SPD methods in order to thoroughly understand the strain behavior and deformation analysis in the processed samples. Overall, it is expected that this upcoming review paper will be a motivation for the community since undoubtedly, the CEC of  Mg-based alloys and composites needs further advancement to find its actual position in industrial applications.

Article Link: https://authors.elsevier.com/a/1fixMI6yuEvvE

Fig. 12. The schematic representation of temperature- and orientation-dependent failure mechanisms of AZ31 Mg alloy under tension (GBs: grain boundaries and TBs: twin boundaries)

Fig. 18. The EBSD results on the as-extruded Mg-8.4Gd-2.3Y-0.2Zr alloy: (a) inverse pole figure (IPF) map, (b) distribution of the dynamicrecrystallized grain size, (c) pole figures of the whole, the dynamic-recrystallized (DRXed), and undynamic-recrystallized (unDRXed) microstructures. Note that the extrusion direction (ED) in (a) and (c) is in the vertical direction and the vertical direction to the map, respectively.


Fig.25. Microstructure evolution of a recrystallized mantle during dynamic recrystallization (DRX) for the consecutive necklace formation: (a) the parent grains without DRX grains in the strains below εc, (b) the formation of the first necklace at prior grain boundaries, (c) the expansion of the second necklace and the DRX volume into the grain interior, (d & e) expansion of the DRX volume to consume the grain interior, and (f) the corresponding flow curve.


Fig. 30. CEC process of the AZ91D Mg composite reinforced by SiC nanoparticles: (a) schematic representation of the twinning-assisted grain refinement mechanism during the process, (b1) matrix grain size and (b2) the corresponding area fraction of the processed composite, and (c) statistical analysis on the distribution of the nanoparticles including (c1) average particle distance and (c2) particle numbers within a specific area of 4 × 4 μm2 


Fig. 36. (a) Microstructural characteristics of the ZK61 Mg alloy including (a1) inverse pole figure map with representative crystallographic relationships between the parent grain (dark) and twinning (red), (a2) frequency as a function of misorientation map, and (a3) {0 0 0 2}, {1 0 1 0}, and {1 1 2 0} pole figures, (b) room-temperature mechanical behaviors of the as-received alloy in tension and compression including (b1) true stress–strain curves and (b2) strain-hardening curves, (c) room-temperature true stress–strain curves of the CEC-processed alloy at different cycles in (c1) tension and (c2) compression, (d) room-temperature hardening curves of the CEC-processed alloy at different cycles in (d1) tension and (d2) compression, and (e) Schmid factors of basal slip (mbas.), {1 1 2 2} pyramidal 〈c + a〉 slip (mpyr.), and {1 0 1 2} twinning (mtwin.) in tension and compression for the initial, second, and fourth cycles. Note that LAGBs and HAGBs denote low-angle and high-angle grain boundaries, respectively. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)


Fig. 43. Mechanical and microstructural behavior of Mg-1.5Zn-0.25Gd alloy during the CEC process: (a) tensile stress–strain curves in different pass numbers, (b) {0 0 0 1} pole figures of the processed alloy after (b1) two passes (b2) four passes, (b3) eight passes, and (b4) the Schmid factor distribution map of the mentioned samples, and (c) schematic representation of the grain refinement during the process (the strain accumulation increases from c1 to c3).

Fig. 51. Effect of lithium content on the corrosion behavior of Mg-Li alloys: (a) weight loss of Mg-1Li, Mg-3Li, and Mg-5Li alloys subjected to immersion in 0.1 M NaCl for 3 days, (b) SEM observations of sample surfaces after removing the corrosion products in (b1) Mg-1Li, (b2) Mg-3Li, and (b3) Mg-5Li subjected to immersion in 0.1 M NaCl for 2 h, (c) potentiodynamic polarization curves and Nyquist plots (electrochemical impedance spectroscopy spectra) of Mg-1Li, Mg-3Li, and Mg-5Li alloys measured in 0.1 M NaCl solution, and (d) representative 3D confocal laser scanning microscopy images of Mg-1Li, Mg-3Li, and Mg-5Li alloys subjected to immersion in 0.1 M NaCl solution for 4 h, 8 h, and 16 h . Note that figure 

(b4), (b5), and (b6) are higher-magnification observations of the localization in figure (b1), (b2), and (b3), respectively.


Fig. 56. (a) Contours of the effective plastic strain (EPS) distribution in the CCEE processing of AZ91 Mg alloy (a1) during the first pass and at the end of (a2) the second and (a3) the third passes, and (b) cellular automaton finite element method of the processed microstructure with different positions of (b1) initial sample, (b2-b4) the deformed sample in points “A”, “B”, and “C”, respectively. Note that these points correspond to the labeled contraction and extrusion zones in (b).

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