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1. The Microstructural Evolution and Corrosion Behavior of Zn-Mg Alloys and Hybrids Processed Using High-Pressure Torsion

   https://doi.org/10.3390/ma17010270  

   Tanji, Ayoub; Hermawan, Hendra; Boehlert, Carl J. (January 2024, Materials)

   Zinc (Zn) alloys, particularly those incorporating magnesium (Mg), have been explored as potential bioabsorbable metals. However, there is a continued need to enhance the corrosion characteristics of Zn-Mg alloys to fulfill the requirements for biodegradable implants. This work involves a corrosion behavior comparison between severe-plastic-deformation (SPD) processed cast Zn-Mg alloys and their hybrid counterparts, having equivalent nominal compositions. The SPD processing technique used was high-pressure torsion (HPT), and the corrosion behavior was studied as a function of the number of turns (1, 5, 15) for the Zn-3Mg (wt.%) alloy and hybrid and as a function of composition (Mg contents of 3, 10, 30 wt.%) for the hybrid after 15 turns. The results indicated that HPT led to multimodal grain size distributions of ultrafine Mg-rich grains containing MgZn2 and Mg2Zn11 nanoscale intermetallics in a matrix of coarser dislocation-free Zn-rich grains. A greater number of turns resulted in greater corrosion resistance because of the formation of the intermetallic phases. The HPT hybrid was more corrosion resistant than its alloy counterpart because it tended to form the intermetallics more readily than the alloy due to the inhomogeneous conditions of the materials before the HPT processing as well as the non-equilibrium conditions imposed during the HPT processing. The HPT hybrids with greater Mg contents were less corrosion resistant because the addition of Mg led to less noble behavior. 

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2. Multi-Scale Microstructural Characterization of Aluminum Alloys Subject to Advanced Processing Techniques for Improving Mechanical Properties

   Wu, Yun-Hsuan (August 2025, Oregon State University)

   This work presents a multi-scale microstructural characterization of aluminum alloys processed by high-pressure torsion (HPT) and cold angular rolling process (CARP) to improve their mechanical properties. Mechanical properties such as microhardness and tensile strength were correlated with microstructural features. To understand the processing-structure-property relationships, characterization methods spanning nano- to millimeter scales were used, including X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), electron backscatter diffraction (EBSD), transmission electron microscopy (TEM), and scanning transmission electron microscopy (STEM) EDS. TEM and STEM EDS were used to show that HPT of a Mg sheet sandwiched between Al sheets successfully produced a supersaturated solid solution (SSSS) of Mg in Al and several Al-Mg intermetallic phases, leading to significant grain refinement and increases in microhardness over pure Al. Although CARP has potential to induce the severe plastic deformation (SPD), the CARP system used in this work was not able to achieve SPD aluminum alloys. However, SEM EBSD characterization shows that CARP achieves an increase of the low-angle grain boundaries (LAGBs) and geometrically necessary dislocation (GND) density in Al-1043,which improves the mechanical properties. Moreover, a preliminary study was conducted on CAPR processed Al-6061 alloys to understand the synergistic effects precipitation and CARP-processing on the microstructure and properties. This research provides the critical insights into the capabilities and current limitations of CARP as a continuous SPD technique for aluminum alloys, and demonstrate the importance of integrated multi-scale characterization in understanding advanced materials processing. 

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3. Severe plastic deformation for producing Superfunctional ultrafine-grained and heterostructured materials: An interdisciplinary review

   https://doi.org/10.1016/j.jallcom.2024.174667  

   Edalati, Kaveh; Ahmed, Anwar Q; Akrami, Saeid; Ameyama, Kei; Aptukov, Valery; Asfandiyarov, Rashid N; Ashida, Maki; Astanin, Vasily; Bachmaier, Andrea; Beloshenko, Victor; et al (May 2024, Journal of Alloys and Compounds)

   Ultrafine-grained and heterostructured materials are currently of high interest due to their superior mechanical and functional properties. Severe plastic deformation (SPD) is one of the most effective methods to produce such materials with unique microstructure-property relationships. In this review paper, after summarizing the recent progress in developing various SPD methods for processing bulk, surface and powder of materials, the main structural and microstructural features of SPD-processed materials are explained including lattice defects, grain boundaries and phase transformations. The properties and potential applications of SPD-processed materials are then reviewed in detail including tensile properties, creep, superplasticity, hydrogen embrittlement resistance, electrical conductivity, magnetic properties, optical properties, solar energy harvesting, photocatalysis, electrocatalysis, hydrolysis, hydrogen storage, hydrogen production, CO2 conversion, corrosion resistance and biocompatibility. It is shown that achieving such properties is not currently limited to pure metals and conventional metallic alloys, and a wide range of materials are processed by SPD, including high-entropy alloys, glasses, semiconductors, ceramics and polymers. It is particularly emphasized that SPD has moved from a simple metal processing tool to a powerful means for the discovery and synthesis of new superfunctional metallic and nonmetallic materials. The article ends by declaring that the borders of SPD have been extended from materials science and it has become an interdisciplinary tool to address scientific questions such as the mechanism of geological and astronomical phenomena and the origin of life. Keywords: Severe plastic deformation (SPD); Nanostructured materials; Ultrafine grained (UFG) materials; Gradient-structured materials, High-pressure torsion (HPT) 

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4. Recent Developments in the Processing of Advanced Materials Using Severe Plastic Deformation

   https://doi.org/10.4028/www.scientific.net/MSF.1016.3  

   Kawasaki, Megumi; Figueiredo, Roberto B.; Langdon, Terence G. (January 2021, Materials Science Forum)

   null (Ed.)

   The processing of bulk metals through the application of severe plastic deformation (SPD), using procedures such as equal-channel angular pressing (ECAP) and high-pressure torsion (HPT), is now well established for the fabrication of materials with exceptionally small grain sizes, usually in the submicrometer range and often having grain sizes at the nanometer level. These grain sizes cannot be achieved using thermo-mechanical processing or any conventional processing techniques. Recently, these procedures have been further developed to process alternative advanced materials. For example, by stacking separate disks within the HPT facility for the synthesis of bulk nanocrystalline metastable alloys where it is possible to achieve exceptionally high hardness, or by pressing powders or metallic particles in order to obtain new and novel nanocomposites exhibiting unusual properties. 

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5. Severe Plastic Deformation of Ceramics by High-Pressure Torsion: Review of Principles and Applications

   Edalati, Kaveh; Hidalgo, Jimenez J; Nguyen, Thanh T; Sena, Hadi; Enikeev, Nariman; Rogl, Gerda; Levitas, Valery I; Horita, Zenji; Zehetbauer, Michael J; Valiev, Ruslan Z; et al (July 2025, Annual review of materials research)

   Ceramics are typically brittle at ambient conditions due to their covalent or ionic bonding and limited dislocation activities. While plasticity, and occasionally superplasticity, can be achieved in ceramics at high temperatures through thermally activated phenomena, creep, and grain boundary sliding, their deformation at ambient temperature and pressure remains challenging. Processing under high pressure via the high-pressure torsion (HPT) method offers new pathways for severe plastic deformation (SPD) of ceramics. This article reviews recent advances in HPT processing of ceramics, focusing primarily on traditional ceramics (e.g., oxides, carbides, nitrides, oxynitrides) and to a lesser extent advanced ceramics (e.g., silicon, carbon, perovskites, clathrates). Key structural and microstructural features of SPD-processed ceramics are discussed, including phase transformations and the generation of nanograins and defects such as vacancies and dislocations. The properties and applications of these deformed ceramics are summarized, including powder consolidation, photoluminescence, bandgap narrowing, photovoltaics, photocatalysis (dye degradation, plastic waste degradation, antibiotic degradation, hydrogen production, CO2 conversion), electrocatalysis, thermoelectric performance, dielectric performance, and ion conductivity for Li ion batteries. Additionally, the article highlights the role of HPT in synthesizing novel materials, such as high-entropy ceramics (particularly high-entropy oxides), black oxides, and high-pressure polymorphs, which hold promise for energy and environmental applications. 

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