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.

Microstructure and Thermal Stability of Copper - Carbon Nanotube Composites Consolidated by High Pressure Torsion

2012 ◽  
Vol 729 ◽  
pp. 228-233 ◽  
Author(s):  
P. Jenei ◽  
E.Y. Yoon ◽  
Jenő Gubicza ◽  
Hyoung Seop Kim ◽  
J.L. Lábár ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Grain Size ◽  
High Pressure ◽  
Dislocation Density ◽  
High Pressure Torsion ◽  
Lattice Defect ◽  
Taylor Formula ◽  
Processing Temperature ◽  
Pure Cu ◽  
Thermal Stability Of

Blends of Cu powders and 3 vol. % carbon nanotubes (CNTs), and an additional sample from pure Cu powder were consolidated by High Pressure Torsion (HPT) at room temperature (RT) and 373 K. The grain size, the lattice defect densities as well as the hardness of the pure and composite materials were determined. Due to the pinning effect of CNTs, the dislocation density is about three times larger, while the grain size is about half of that obtained in the sample consolidated from the pure Cu powder. The increase of the HPT-processing temperature from RT to 373 K resulted in only a slight increase of the grain size in the Cu-CNT composite while the dislocation density and the twin boundary frequency were reduced significantly. The flow stress obtained experimentally agrees well with the value calculated by the Taylor-formula indicating that the strength in both pure Cu and Cu-CNT composites is determined mainly by the interaction between dislocations. The addition of CNTs to Cu yields a significantly better thermal stability of the UFG matrix processed by HPT.

Microstructure and Properties of Ultrafine Grained Cu-0.73%Cr Alloy after High Pressure Torsion

2011 ◽  
Vol 391-392 ◽  
pp. 385-389 ◽  
Author(s):  
Kun Xia Wei ◽  
Wei Wei ◽  
Igor V. Alexandrov ◽  
Qing Bo Du ◽  
Jing Hu
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Electrical Conductivity ◽  
Grain Size ◽  
High Pressure ◽  
High Pressure Torsion ◽  
Aging Treatment ◽  
High Thermal Stability ◽  
Subsequent Aging ◽  
Ultrafine Grained

Microstructure, mechanical properties and electrical conductivity in Cu-0.73%Cr alloy after HPT process and the subsequent aging treatment have been investigated. Ultrafine grained structure with the grain size ~150 nm has been achieved after the HPT and the subsequent aging treatment. Ultrafine grains with some growth twins were preserved in the overaged state, showing high thermal stability. The peak microhardness and tensile strength of Cu-0.73%Cr alloy after the HPT was found at 480 °C for 2 hours. Electrical conductivity shows an increase trend in the different aging states.

scholarly journals Thermal stability of a nanocrystalline HfNbTiZr multi-principal element alloy processed by high-pressure torsion

2020 ◽  
Vol 168 ◽  
pp. 110550 ◽  
Author(s):  
Pham Tran Hung ◽  
Megumi Kawasaki ◽  
Jae-Kyung Han ◽  
János L. Lábár ◽  
Jenő Gubicza
Keyword(s):  
Thermal Stability ◽  
High Pressure ◽  
High Pressure Torsion ◽  
Principal Element ◽  
Thermal Stability Of

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.

Enhanced Thermal Stability and Mechanical Properties of Ultrafine-Grained Aluminum Alloy

2010 ◽  
Vol 667-669 ◽  
pp. 331-336 ◽  
Author(s):  
Rinat K. Islamgaliev ◽  
Marina A. Nikitina ◽  
Aidar F. Kamalov
Keyword(s):  
Thermal Stability ◽  
Aluminum Alloy ◽  
Volume Fraction ◽  
High Pressure Torsion ◽  
Coarse Grained ◽  
Dynamic Precipitation ◽  
Ultrafine Grained ◽  
The Mean ◽  
Fatigue Endurance ◽  
Thermal Stability Of

The paper reports on microstructure, strength and fatigue of ultrafine-grained (UFG) samples of the Al-Cu-Mg-Si aluminum alloy processed by high pressure torsion (HPT) at various temperatures. Application of the HPT treatment led to strong grain refinement, as well as to a raise of the mean-root square strains and dynamic precipitation. In case of optimal HPT treatment the UFG samples have demonstrated the enhanced thermal stability, an increase in ultimate tensile strength in 2.5 times and enhancement in fatigue endurance limit by 20 % in comparison with coarse-grained alloy subjected to standard treatment. It is shown that the regime of the HPT treatment governs the volume fraction of precipitates and segregations, thereby affecting a grain size and thermal stability of ultrafine-grained structure.

Thermal stability of pure bcc Zr fabricated by high pressure torsion

2010 ◽  
Vol 64 (2) ◽  
pp. 211-214 ◽  
Author(s):  
M.T. Pérez-Prado ◽  
A. Sharafutdinov ◽  
A.P. Zhilyaev
Keyword(s):  
Thermal Stability ◽  
High Pressure ◽  
High Pressure Torsion ◽  
Thermal Stability Of
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