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Superplasticity, Plastic Deformation, and Grain Refinement of Metals and Alloys

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Metals and Alloys".

Deadline for manuscript submissions: closed (20 April 2024) | Viewed by 3108

Special Issue Editor

1. School of Materials Science and Engineering, Northeastern University, Shenyang 110819, China
2. State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819, China
Interests: magnesium-lithium alloy and aluminum-magnesium alloy; superplasticity; deformation mechanism; mechanical behavior; microstructure; modelling; severe plastic deformation such as multidirectional forging (MDF), friction stir processing(FSP), and conform-ECAP; thermomechanical processing such as rolling and continuous casting-extrusion; strengthening mechanism

Special Issue Information

Dear Colleagues,

Superplasticity (SP) is the exceptional capability of materials including metals and alloys to exhibit high elongation or ductility, typically more than 400% elongation. Quasi-superplasticity usually obtains 200–300% elongation. Superplastic forming can manufacture alloy components with a complex shape on small tonnage equipment. Here, the alloys include aluminum alloys, magnesium alloys, titanium alloys, steel, zinc alloys, superalloys, high-entropy alloys, and so forth. This special issue plans to give an overview of the most recent advances in the field of metallic SP research. It aims to bring forward new ideas and innovation knowledge relevant to SP of metals and alloys, and explore the opportunity of superplastic forming.

Potential topics include but are not limited to:

  • Superplastic ductility achieved in a variety of alloys;
  • Underlying deformation mechanism of superplasticity and dislocation creep;
  • Mechanical behavior and microstructural evolution of various alloys deformed at elevated temperature;
  • Modelling of superplasticity and dislocation creep;
  • Grain refinement and its evolution mechanism by various approaches of severe plastic deformation and conventional thermomechanical processing;
  • Superplastic forming, and so on.

Dr. Furong Cao
Guest Editor

Manuscript Submission Information

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Keywords

  • alloy
  • superplasticity
  • deformation mechanism
  • mechanical behavior
  • microstructure
  • modeling
  • severe plastic deformation
  • thermomechanical processing
  • superplastic forming

Published Papers (2 papers)

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Research

15 pages, 22933 KiB  
Article
Effect of Boron on the Microstructure, Superplastic Behavior, and Mechanical Properties of Ti-4Al-3Mo-1V Alloy
by Maria N. Postnikova, Anton D. Kotov, Andrey I. Bazlov, Ahmed O. Mosleh, Svetlana V. Medvedeva and Anastasia V. Mikhaylovskaya
Materials 2023, 16(10), 3714; https://doi.org/10.3390/ma16103714 - 13 May 2023
Cited by 4 | Viewed by 1399
Abstract
The decrease of superplastic forming temperature and improvement of post-forming mechanical properties are important issues for titanium-based alloys. Ultrafine-grained and homogeneous microstructure are required to improve both processing and mechanical properties. This study focuses on the influence of 0.01–2 wt.% B (boron) on [...] Read more.
The decrease of superplastic forming temperature and improvement of post-forming mechanical properties are important issues for titanium-based alloys. Ultrafine-grained and homogeneous microstructure are required to improve both processing and mechanical properties. This study focuses on the influence of 0.01–2 wt.% B (boron) on the microstructure and properties of Ti-4Al-3Mo-1V (wt.%) alloys. The microstructure evolution, superplasticity, and room temperature mechanical properties of boron-free and boron-modified alloys were investigated using light optical microscopy, scanning electron microscopy, electron backscatter diffraction, X-ray diffraction analysis, and uniaxial tensile tests. A trace addition of 0.01 to 0.1 wt.% B significantly refined prior β-grains and improved superplasticity. Alloys with minor B and B-free alloy exhibited similar superplastic elongations of 400–1000% in a temperature range of 700–875 °C and strain rate sensitivity coefficient m of 0.4–0.5. Along with this, a trace boron addition provided a stable flow and effectively reduced flow stress values, especially at low temperatures, that was explained by the acceleration of the recrystallization and globularization of the microstructure at the initial stage of superplastic deformation. Recrystallization-induced decrease in yield strength from 770 MPa to 680 MPa was observed with an increase in boron content from 0 to 0.1%. Post-forming heat treatment, including quenching and ageing, increased strength characteristics of the alloys with 0.01 and 0.1% boron by 90–140 MPa and insignificantly decreased ductility. Alloys with 1–2% B exhibited an opposite behavior. For the high-boron alloys, the refinement effect of the prior β-grains was not detected. A high fraction of borides of ~5–11% deteriorated the superplastic properties and drastically decreased ductility at room temperature. The alloy with 2% B demonstrated non-superplastic behavior and low level of strength properties; meanwhile, the alloy with 1% B exhibited superplasticity at 875 °C with elongation of ~500%, post-forming yield strength of 830 MPa, and ultimate tensile strength of 1020 MPa at room temperature. The differences between minor boron and high boron influence on the grain structure and properties were discussed and the mechanisms of the boron influence were suggested. Full article
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15 pages, 3861 KiB  
Article
Room Temperature Strengthening and High-Temperature Superplasticity of Mg-Li-Al-Sr-Y Alloy Fabricated by Asymmetric Rolling and Friction Stir Processing
by Furong Cao, Chao Xiang, Shuting Kong, Nanpan Guo and Huihui Shang
Materials 2023, 16(6), 2345; https://doi.org/10.3390/ma16062345 - 15 Mar 2023
Cited by 4 | Viewed by 1277
Abstract
Magnesium-lithium alloy is the lightest alloy to date. To explore its room temperature strength and high-temperature ductility, a plate of a new fine-grained Mg-9.13Li-3.74Al-0.31Sr-0.11Y alloy was fabricated by asymmetric rolling, and the rolled plate was subjected to friction stir processing (FSP). The microstructure [...] Read more.
Magnesium-lithium alloy is the lightest alloy to date. To explore its room temperature strength and high-temperature ductility, a plate of a new fine-grained Mg-9.13Li-3.74Al-0.31Sr-0.11Y alloy was fabricated by asymmetric rolling, and the rolled plate was subjected to friction stir processing (FSP). The microstructure and mechanical properties at room and elevated temperatures were investigated by optical microscopy, X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), and tensile tester. Grain refinement with an average grain size in the α-Mg phase of 1.65 μm and an average grain size in the β-Li phase of 4.24 μm was achieved in the water-cooled FSP alloy. For room temperature behavior, the ultimate tensile strength of 208 ± 4 MPa, yield strength of 193 ± 2 MPa, and elongation of 48.2% were obtained in the water-cooled FSP alloy. XRD and EDS analyses revealed that the present alloy consists of α-Mg and β-Li phases, Al2Y, Al4Sr, MgLi2Al, and AlLi intermetallic compounds. For high-temperature behavior, the maximum superplasticity or ductility of 416% was demonstrated in this fine-grained alloy with an average grain size of 10 μm at 573 K and 1.67 × 10−3 s−1. A power-law constitutive equation was established. The stress exponent was 2.29 (≈2) (strain rate sensitivity 0.44), and the deformation activation energy was 162.02 kJ/mol. This evidence confirmed that the dominant deformation mechanism at elevated temperatures is grain boundary and interphase boundary sliding controlled by lattice diffusion. Full article
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