☆ 4.7 Article

Hot tensile deformation behavior of extruded LAZ532 alloy with heterostructure

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING (2021)

Journal

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

Volume 801, Issue -, Pages -

Publisher

ELSEVIER SCIENCE SA

DOI: 10.1016/j.msea.2020.140412

Keywords

Mg-Li alloy; Hot tensile; Dynamic recrystallization; Deformation mechanism

Funding

National Key Research and Development Program of China [2016YFB0301104]
National Natural Science Foundation of China [51771043]
Programme of Introducing Talents of Discipline Innovation to Universities 2.0 (111 Project 2.0 of China) [BP0719037]

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Abstract

The hot tensile test was performed on an extruded Mg-5Li-3Al-2Zn (LAZ532) alloy with a heterostructure of fibrous extrusion zones (FEZs) and nonfibrous extrusion zones (non-FEZs) coexisted, showing that the alloy exhibited superplastic characteristics at lower strain rates or higher deformation temperatures. The microstructure analysis revealed different deformation behaviors between the FEZs and non-FEZs, with different mechanisms dominating during different stages of deformation. The activation energy was calculated to be around 110.0 kJ/mol, and the hot tensile deformation mechanism involved alternating and coordinated deformation among grain boundary slip, intragranular slip, and dynamic recrystallization (DRX).

Hot tensile test was performed at deformation conditions of 150-degrees C300 degrees C and 8.33 x 10(-5) s(-1)similar to 1.67 x 10(-3) s(-1), respectively, to systematically study the microstructure development and deformation mechanism of extruded Mg-5Li-3Al-2Zn (LAZ532) alloy with a heterostructure of both the fibrous extrusion zones (FEZs) and nonfibrous extrusion zones (non-FEZs) coexisted. The results showed that the peak stresses decreased gradually, while the fracture strains increased gradually with the decrease of strain rates or the increase of deformation temperatures, and the alloy exhibited superplastic characteristics at deformation conditions of 300 degrees C and 8.33 x 10(-5) s(-1) similar to 1.67 x 10(-3) s(-1). By microstructure observation, the alloy showed that in the initial deformation stage, the deformation of the grains in the FEZs was prior to that in the non-FEZs. In the middle deformation stage, the deformation of the grains in the FEZs was dominated by intragranular slip and accompanied with grain boundary slip (GBS), while the deformation of the grains in the non-FEZs was dominated by GBS and accompanied with intragranular slip. In the later deformation stage, the continuous dynamic recrystallization (CDRX) generated in the coarse lamellar grains in the FEZs due to dislocation pile-up, in contrast, the discontinuous dynamic recrystallization (DDRX) generated at the grain boundaries in the non-FEZs. Moreover, based on theoretical calculation and result analysis, the activation energy was about 110.0 kJ/mol, and the hot tensile deformation mechanism was each other alternating and coordinated deformation mechanism among GBS, intragranular slip and dynamic recrystallization (DRX).

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Hot tensile deformation mechanism and microstructure evolution of Mg-2Nd alloy with heterostructure

Ting Yang, Xiaoqiang Li, Lei Zhang, Jinhui Wang, Peipeng Jin

Summary: The deformation mechanism and microstructure evolution of the Mg-2Nd alloy during hot tensile deformation were investigated. It was found that the peak stress decreases and the elongation to fracture increases with increasing deformation temperature. The alloy contains fibrous extrusion zones (FEZs) and non-fibrous extrusion zones (non-FEZs), with the microstructure deformation in the FEZs being more pronounced. In the initial deformation stage, grain deformation occurs primarily in the FEZs, while recrystallization occurs in both FEZs and non-FEZs in the later deformation stage. The dominant deformation mechanism in the FEZs is intragranular slip, supplemented by grain boundary slip (GBS), while the dominant deformation mechanism in the non-FEZs is GBS, with coordinated intragranular slip. The recrystallization mechanism in the FEZs is continuous dynamic recrystallization (CDRX), while it is discontinuous dynamic recrystallization (DDRX) in the non-FEZs. Thus, the dominant hot tensile deformation mechanisms of the alloys alternate between intragranular slip, GBS, and dynamic recrystallization (DRX).

MATERIALS CHARACTERIZATION (2022)