ORALS

SESSION: MagnesiumFriPM1-R4	Intl Symp. on Next Generation Magnesium Alloys and Their Applications for Sustainable Development
Fri Oct, 25 2019 / Room: Adonis
Session Chairs: Takao Tsumuraya; Session Monitor: TBA

15:15: [MagnesiumFriPM108]
Deformation Behavior of Directionally Solidified Mg/LPSO Alloy with Respect to its Lamellar Structure
Daria Drozdenko¹ ; Kristián Máthis² ; Michiaki Yamasaki³ ; Stefanus Harjo⁴ ; Wu Gong⁵ ; Kazuya Aizawa⁶ ; Yoshihito .kawamura⁷ ; ¹Magnesium Research Center, Kumamoto University, Kumamoto, Japan; ²Department of Physics of Materials, Charles University, Prague, Czech Republic; ³Kumamoto university, Kumamoto, Japan; ⁴Japan Atomic Energy Agency, Naka-gun, Japan; ⁵Kyoto University, Tokai-mura, Japan; ⁶Japan Atomic Energy Agency, Tokai-mura, Japan; ⁷Kumamoto University, Kumamoto, Japan;
Paper Id: 308 [Abstract]

Recently, a new generation of Mg alloys with an LPSO phase have received considerable attention due to their enhanced mechanical and promising high-temperature properties compared to the conventional Mg alloys. Nevertheless, those alloys still suffer from anisotropy of mechanical properties. It is generally agreed that besides the dislocation slip, deformation kinking and twinning contribute to the plastic deformation of those alloys. The materials’ parameters (shape and orientation of LPSO phase, grain size, texture) as well as the experimental conditions (loading direction, temperature etc.) are factors on which deformation kinking depends for it to be considered common for Mg/LPSO alloys. The conditions for kink formation in Mg-LPSO alloys and their dependence on temperature, however, are still under consideration. In this present work, a directionally solidified Mg -24 wt.% Y- 12wt.% Zn alloy having a lamellar structure elongated along the solidification direction was investigated. In order to reveal the effect of orientation on deformation behavior, uniaxial compression tests were performed parallel and perpendicular to the LSPO lamellae. Active deformation mechanisms were revealed by combination of two advanced in-situ techniques: acoustic emission and neutron diffraction. Detailed microscopy observations by optical and scanning electron microscopy (including EBSD, BSD imaging and IGMA) were performed for getting information about microstructure changes (e.g. twin and kink formation) with respect to a lamellar structure and crystallographic orientation. Kinking was found to be a dominant deformation mechanism during compression along the lamellar structure, resulting in high yield strength. In the case of loading perpendicular to lamellae, kinking was limited to well oriented lamellae and rather higher activity of the <c+a> dislocation slip was observed. IGMA analysis has shown that all observed kinks in both orientations were found to be of <1-100>-and <1-210>-rotation types.

References:
[1] Kawamura et al. Mater Trans 42(7) 2001 1172-1176
[2] Hagihara et al. Intermetallics 18 (2010) 267-276
[3] Yamasaki et al. Acta Mater, 61 (2013) 2065-2076
[4] Garces et al. Int. J. Plast. 106 (2018) 107-128
[5] W.Gong et al. Int J Plast 111 (2018) 288-306

SESSION: MagnesiumFriPM2-R4	Intl Symp. on Next Generation Magnesium Alloys and Their Applications for Sustainable Development
Fri Oct, 25 2019 / Room: Adonis
Session Chairs: TBA Session Monitor: TBA

16:20: [MagnesiumFriPM210]
Acoustic Emission Study of Active Deformation Mechanisms in Mg Alloys
Patrik Dobron¹ ; Daria Drozdenko² ; Klaudia Horvath¹ ; Juraj Olejnak¹ ; Jan Bohlen³ ; ¹Charles University, Prague, Prague, Czech Republic; ²Magnesium Research Center, Kumamoto University, Kumamoto, Japan; ³Helmholtz-Zentrum Geesthacht, Geesthacht, Germany;
Paper Id: 319 [Abstract]

The activity of individual deformation mechanisms during deformation tests of wrought Mg alloys was investigated using the acoustic emission (AE) technique. The investigated alloys exhibited a typical basal texture with basal planes oriented nearly parallel to the extrusion or rolling direction. Deformation tests were performed at room temperature and the obtained results are supported by microstructure evolution analysis provided by electron backscattered diffraction (EBSD). The AE signal analysis correlates the microstructure and the stress-strain curves to the active deformation mechanisms quite well. To determine the dominant deformation mechanism in a given time period, the adaptive sequential k-means (ASK) clustering was applied. X-ray diffraction was used to characterize the deformation texture before and after the test in order to obtain comprehensive data for texture characterization.