A novel severe plastic deformation method and its effect on microstructure, texture and mechanical properties of Mg-Gd-Y-Zn-Zr alloy

In this paper, cyclic expansion extrusion with an asymmetrical extrusion cavity (CEE-AEC) was proposed as a novel severe plastic deformation process for fabricating bulk ultrafine-grained (UFG) metals. Increasing the size of the processed sample and introducing the shear strain by attaching an asymm...

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Bibliographic Details
Published in:Journal of alloys and compounds 2020-05, Vol.822, p.153698, Article 153698
Main Authors: Yan, Zhaoming, Zhang, Zhimin, Li, Xubin, Xu, Jian, Wang, Qiang, Zhang, Guanshi, Zheng, Jie, Fan, Hongzhi, Xu, Kaihua, Zhu, Jiaxuan, Xue, Yong
Format: Article
Language:English
Subjects:
Asymmetry
Basal plane
Cyclic expansion extrusion with an asymmetrical extrusion cavity
Deformation effects
Dynamic recrystallization
Elongation
Extrusion
Gadolinium
Grain refinement
Long-period stacking ordered phases
Magnesium
Mechanical properties
Mg-Gd-Y-Zn-Zr
Microstructure
Nucleation
Plastic deformation
Room temperature
Shear strain
Tensile tests
Texture
Ultimate tensile strength
Ultrafine-grained materials
Ultrafines
Yield strength
Zinc
Zirconium base alloys
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Summary:In this paper, cyclic expansion extrusion with an asymmetrical extrusion cavity (CEE-AEC) was proposed as a novel severe plastic deformation process for fabricating bulk ultrafine-grained (UFG) metals. Increasing the size of the processed sample and introducing the shear strain by attaching an asymmetrical extrusion cavity are the core advantages of this technology. The CEE-AEC process was applied to Mg-13Gd-4Y–2Zn-0.4Zr alloys for four passes deformation with the decreasing temperature, and then the microstructure evolution, texture analysis, and mechanical properties were investigated. Microstructure results show that a dramatical grain refinement is achieved from initial value of 24 ± 0.3 μm to 1.4 ± 0.3 μm which is mainly led by continuous dynamic recrystallization (CDRX) and discontinuous dynamic recrystallization (DDRX) as well as the particle-stimulated nucleation (PSN) induced by interdendritic long-period stacking ordered (LPSO) phases. With increasing CEE-AEC passes, the intensities of basal texture are gradually weakened, and the basal plane tends to incline to transverse and normal directions with different degrees of different passes, leading to a remarkable increase in Schmid factor for the activation of basal slip system. Tensile tests at room temperature (RT) indicate that the samples after three-passes of CEE-AEC exhibit the best comprehensive mechanical properties with tensile yield strength (TYS) of 302 MPa, ultimate tensile strength (UTS) of 330 MPa, and fracture elongation of 6.1%, which are mainly ascribed to the grain refinement, broken of interdendritic block-shaped LPSO phases, and texture modification. •A novel SPD method entitled CEE-AEC was proposed.•The Mg-13Gd-4Y–2Zn-0.4Zr alloy was processed by CEE-AEC with consecutive four passes deformation.•A significant grain refinement from initial 24 ± 0.3 μm to 1.4 ± 0.3 μm was obtained.•Continuous and discontinuous dynamic recrystallizations took place during CEE-AEC.•The mechanical properties were contributed from the competitive of fine grains strengthening and texture modification.
ISSN:0925-8388
1873-4669
DOI:10.1016/j.jallcom.2020.153698