scholarly journals Critical Temperature in Bulk Ultrafine-Grained Superconductors of Nb, V, and Ta Processed by High-Pressure Torsion

2019 ◽  
Vol 60 (7) ◽  
pp. 1367-1376 ◽  
Author(s):  
Terukazu Nishizaki ◽  
Kaveh Edalati ◽  
Seungwon Lee ◽  
Zenji Horita ◽  
Tadahiro Akune ◽  
...  
Keyword(s):  
High Pressure ◽  
Critical Temperature ◽  
High Pressure Torsion ◽  
Ultrafine Grained

Percolating porosity in ultrafine grained copper processed by High Pressure Torsion

2013 ◽  
Vol 114 (18) ◽  
pp. 183509 ◽  
Author(s):  
Matthias Wegner ◽  
Jörn Leuthold ◽  
Martin Peterlechner ◽  
Daria Setman ◽  
Michael Zehetbauer ◽  
...  
Keyword(s):  
High Pressure ◽  
High Pressure Torsion ◽  
Ultrafine Grained

The Processing of Ultrafine-Grained Materials Using High-Pressure Torsion

2007 ◽  
Vol 558-559 ◽  
pp. 1283-1294 ◽  
Author(s):  
Cheng Xu ◽  
Z. Horita ◽  
Terence G. Langdon
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
High Pressure ◽  
High Pressure Torsion ◽  
Metallic Materials ◽  
Grain Sizes ◽  
Ultrafine Grained ◽  
Wide Range ◽  
Ultrafine Grained Materials ◽  
Thin Disks

It is now well-established that processing through the application of severe plastic deformation (SPD) leads to a significant reduction in the grain size of a wide range of metallic materials. This paper examines the fabrication of ultrafine-grained materials using high-pressure torsion (HPT) where this process is attractive because it leads to exceptional grain refinement with grain sizes that often lie in the nanometer or submicrometer ranges. Two aspects of HPT are examined. First, processing by HPT is usually confined to samples in the form of very thin disks but recent experiments demonstrate the potential for extending HPT also to bulk samples. Second, since the strains imposed in HPT vary with the distance from the center of the disk, it is important to examine the development of inhomogeneities in disk samples processed by HPT.

Mechanical and biological behavior of ultrafine-grained Ti alloy aneurysm clip processed using high-pressure torsion

2017 ◽  
Vol 68 ◽  
pp. 203-209 ◽  
Author(s):  
Ho Yong Um ◽  
Byung Ho Park ◽  
Dong-Hyun Ahn ◽  
Mohamed Ibrahim Abd El Aal ◽  
Jaechan Park ◽  
...  
Keyword(s):  
High Pressure ◽  
High Pressure Torsion ◽  
Biological Behavior ◽  
Ti Alloy ◽  
Aneurysm Clip ◽  
Ultrafine Grained

Thermal Stability of Ultrafine-Grained Pure Titanium Processed by High-Pressure Torsion

2021 ◽  
Vol 1016 ◽  
pp. 338-344
Author(s):  
Wan Ji Chen ◽  
Jie Xu ◽  
De Tong Liu ◽  
De Bin Shan ◽  
Bin Guo ◽  
...  
Keyword(s):  
Activation Energy ◽  
Thermal Stability ◽  
Grain Size ◽  
High Pressure ◽  
Annealing Temperature ◽  
High Pressure Torsion ◽  
Stored Energy ◽  
Ultrafine Grained ◽  
Average Grain Size ◽  
Thermal Stability Of

High-pressure torsion (HPT) was conducted under 6.0 GPa on commercial purity titanium up to 10 turns. An ultrafine-grained (UFG) pure Ti with an average grain size of ~96 nm was obtained. The thermal properties of these samples were studied by using differential scanning calorimeter (DSC) which allowed the quantitative determination of the evolution of stored energy, the recrystallization temperatures, the activation energy involved in the recrystallization of the material and the evolution of the recrystallized fraction with temperature. The results show that the stored energy increases, beyond which the stored energy seems to level off to a saturated value with increase of HPT up to 5 turns. An average activation energy of about 101 kJ/mol for the recrystallization of 5 turns samples was determined. Also, the thermal stability of the grains of the 5 turns samples with subsequent heat treatments were investigated by microstructural analysis and Vickers microhardness measurements. It is shown that the average grain size remains below 246 nm when the annealing temperature is below 500 °C, and the size of the grains increases significantly for samples at the annealing temperature of 600 °C.

scholarly journals Evolution of microstructure and hardness during artificial aging of an ultrafine-grained Al-Zn-Mg-Zr alloy processed by high pressure torsion

2020 ◽  
Vol 55 (35) ◽  
pp. 16791-16805
Author(s):  
Jenő Gubicza ◽  
Moustafa El-Tahawy ◽  
János L. Lábár ◽  
Elena V. Bobruk ◽  
Maxim Yu Murashkin ◽  
...  
Keyword(s):  
High Pressure ◽  
Dislocation Density ◽  
Grain Boundaries ◽  
Artificial Aging ◽  
High Pressure Torsion ◽  
Secondary Phase ◽  
Aging Effect ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Evolution Of Microstructure

Abstract An ultrafine-grained (UFG) Al-4.8%Zn-1.2%Mg-0.14%Zr (wt%) alloy was processed by high pressure torsion (HPT) technique and then aged at 120 and 170 °C for 2 h. The changes in the microstructure due to this artificial aging were studied by X-ray diffraction and transmission electron microscopy. It was found that the HPT-processed alloy has a small grain size of about 200 nm and a high dislocation density of about 8 × 1014 m−2. The majority of precipitates after HPT are Guinier–Preston (GP) zones with a size of ~ 2 nm, and only a few large particles were formed at the grain boundaries. Annealing at 120 and 170 °C for 2 h resulted in the formation of stable MgZn2 precipitates from a part of the GP zones. It was found that for the higher temperature the fraction of the MgZn2 phase was larger and the dislocation density in the Al matrix was lower. The changes in the precipitates and the dislocation density due to aging were correlated to the hardness evolution. It was found that the majority of hardness reduction during aging was caused by the annihilation of dislocations and some grain growth at 170 °C. The aging effect on the microstructure and the hardness of the HPT-processed specimen was compared to that observed for the UFG sample processed by equal-channel angular pressing. It was revealed that in the HPT sample less secondary phase particles formed in the grain boundaries, and the higher amount of precipitates in the grain interiors resulted in a higher hardness even after aging.

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