scholarly journals Hardening mechanism of commercially pure Mg processed by high pressure torsion at room temperature

2014 ◽  
Vol 619 ◽  
pp. 95-106 ◽  
Author(s):  
Xiao Guang Qiao ◽  
Ya Wei Zhao ◽  
Wei Min Gan ◽  
Ying Chen ◽  
Ming Yi Zheng ◽  
...  
Keyword(s):  
High Pressure ◽  
Room Temperature ◽  
High Pressure Torsion ◽  
Hardening Mechanism ◽  
Commercially Pure

GRAIN REFINEMENT AND MICROSTRUCTURE EVOLUTION IN ALUMINUM A2618 ALLOY BY HIGH-PRESSURE TORSION

2016 ◽  
Vol 78 (6-9) ◽  
Author(s):  
Intan Fadhlina Mohamed ◽  
Seungwon Lee ◽  
Kaveh Edalati ◽  
Zenji Horita ◽  
Shahrum Abdullah ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
High Pressure ◽  
Grain Refinement ◽  
Room Temperature ◽  
Rotation Speed ◽  
High Pressure Torsion ◽  
Applied Pressure ◽  
Saturation Level ◽  
Microstructural Refinement ◽  
Average Grain Size

This work presents a study related to the grain refinement of an aluminum A2618 alloy achieved by High-Pressure Torsion (HPT) known as a process of Severe Plastic Deformation (SPD). The HPT is conducted on disks of the alloy under an applied pressure of 6 GPa for 1 and 5 turns with a rotation speed of 1 rpm at room temperature. The HPT processing leads to microstructural refinement with an average grain size of ~250 nm at a saturation level after 5 turns. Gradual increases in hardness are observed from the beginning of straining up to a saturation level. This study thus suggests that hardening due to grain refinement is attained by the HPT processing of the A2618 alloy at room temperature.

scholarly journals The significance of self-annealing at room temperature in high purity copper processed by high-pressure torsion

2016 ◽  
Vol 656 ◽  
pp. 55-66 ◽  
Author(s):  
Yi Huang ◽  
Shima Sabbaghianrad ◽  
Abdulla I. Almazrouee ◽  
Khaled J. Al-Fadhalah ◽  
Saleh N. Alhajeri ◽  
...  
Keyword(s):  
High Pressure ◽  
High Purity ◽  
Room Temperature ◽  
High Pressure Torsion ◽  
Purity Copper

scholarly journals Intragranular deformation mechanisms in calcite deformed by high-pressure torsion at room temperature

2020 ◽  
Vol 114 (2) ◽  
pp. 105-118
Author(s):  
Roman Schuster ◽  
Gerlinde Habler ◽  
Erhard Schafler ◽  
Rainer Abart
Keyword(s):  
High Pressure ◽  
Twin Boundary ◽  
Brittle Failure ◽  
Room Temperature ◽  
High Pressure Torsion ◽  
Confining Pressure ◽  
Temperature Deformation ◽  
Orientation Relationships ◽  
High Confining Pressure ◽  
Confining Pressures

AbstractPolycrystalline calcite was deformed to high strain at room-temperature and confining pressures of 1–4 GPa using high-pressure torsion. The high confining pressure suppresses brittle failure and allows for shear strains >100. The post-deformation microstructures show inter- and intragranular cataclastic deformation and a high density of mechanical e$$ \left\{01\overline{1}8\right\} $$011¯8 twins and deformation lamellae in highly strained porphyroclasts. The morphologies of the twins resemble twin morphologies that are typically associated with substantially higher deformation temperatures. Porphyroclasts oriented unfavorably for twinning frequently exhibit two types of deformation lamellae with characteristic crystallographic orientation relationships associated with calcite twins. The misorientation of the first deformation lamella type with respect to the host corresponds to the combination of one r$$ \left\{10\overline{1}4\right\} $$101¯4 twin operation and one specific f$$ \left\{01\overline{1}2\right\} $$011¯2 or e$$ \left\{01\overline{1}8\right\} $$011¯8 twin operation. Boundary sections of this lamella type often split into two separated segments, where one segment corresponds to an incoherent r$$ \left\{10\overline{1}4\right\} $$101¯4 twin boundary and the other to an f$$ \left\{01\overline{1}2\right\} $$011¯2 or e$$ \left\{01\overline{1}8\right\} $$011¯8 twin boundary. The misorientation of the second type of deformation lamellae corresponds to the combination of specific r$$ \left\{10\overline{1}4\right\} $$101¯4 and f$$ \left\{01\overline{1}2\right\} $$011¯2 twin operations. The boundary segments of this lamella type may also split into the constituent twin boundaries. Our results show that brittle failure can effectively be suppressed during room-temperature deformation of calcite to high strains if confining pressures in the GPa range are applied. At these conditions, the combination of successive twin operations produces hitherto unknown deformation lamellae.

scholarly journals Interface structures in Al-Nb2O5 nanocomposites processed by high-pressure torsion at room temperature

2020 ◽  
Vol 162 ◽  
pp. 110222 ◽  
Author(s):  
Clênio Silva ◽  
Luciano A. Montoro ◽  
Débora A.A. Martins ◽  
Priscila A. Machado ◽  
Pedro Henrique R. Pereira ◽  
...  
Keyword(s):  
High Pressure ◽  
Room Temperature ◽  
High Pressure Torsion ◽  
Interface Structures

Microstructures and Mechanical Property of Ni Processed by High-Pressure Torsion and Their Evolution upon Annealing

2006 ◽  
Vol 114 ◽  
pp. 45-50 ◽  
Author(s):  
Zhi Qing Yang
Keyword(s):  
High Pressure ◽  
Grain Boundaries ◽  
Room Temperature ◽  
High Pressure Torsion ◽  
Small Difference ◽  
Dynamical Evolution ◽  
Peripheral Region ◽  
Lattice Defects ◽  
Grain Sizes ◽  
Xrd And Tem

XRD, TEM, microhardness and thermal analysis were carried out on a series of Ni samples produced by high-pressure torsion (HPT). The evolution of microstructures and their inhomogeneity were investigated. The local microstrain showed dynamical oscillations as a function of the HPT rotations, demonstrating dynamical evolution of lattice defects during the procedure. Both XRD and TEM showed that a small difference in grain sizes remains even after 5 revolutions of HPT with smaller grain sizes at the peripheral region of the sample. The higher microhardness at the peripheral region is the result of the smaller grain sizes and the higher density of lattice defects, compared with the central region. Thermal treatment at a heating rate of 20K/min from room temperature to 473K did not result in decreased microhardness, but increased by about 10% for samples treated with not more than 3 rotations of HPT. The increase in microhardness was attributed to further grain refinement, the formation of a larger fraction of high-angle grain boundaries and grain boundaries being closer to equilibrium after recovery.

Processing Different Magnesium Alloys through HPT

2014 ◽  
Vol 783-786 ◽  
pp. 2617-2622 ◽  
Author(s):  
Livia Raquel C. Malheiros ◽  
Roberto B. Figueiredo ◽  
Terence G. Langdon
Keyword(s):  
Plastic Deformation ◽  
High Pressure ◽  
Magnesium Alloys ◽  
Room Temperature ◽  
High Pressure Torsion ◽  
Structure Refinement ◽  
Hardness Distribution ◽  
Metallic Materials ◽  
Processing Conditions ◽  
Significant Structure

High-Pressure Torsion (HPT) is widely used to refine the structure of metallic materials through the use of severe plastic deformation. This technique is used in this report to process different magnesium alloys using various processing conditions. The high hydrostatic pressure allows processing of these materials at room temperature without cracking. The structure was characterized and hardness distribution was determined at different areas of the processed samples. The results show significant structure refinement and increased hardness. The evolution of the structure and hardness depends on the alloying and HPT processing conditions.

Superplasticity of Ultra-Fine Grained 7075 Alloy Processed by High-Pressure Torsion

2014 ◽  
Vol 794-796 ◽  
pp. 807-810 ◽  
Author(s):  
Seungwon Lee ◽  
Zen Ji Horita
Keyword(s):  
High Pressure ◽  
Room Temperature ◽  
High Pressure Torsion ◽  
Applied Pressure ◽  
Tensile Tests ◽  
Initial Strain ◽  
Strain Rates ◽  
Fine Grained ◽  
Al 7075 ◽  
7075 Alloy

An Al 7075 alloy (5.63mass%Zn-2.56mass%Mg-1.68mass%Cu-0.21mass%Fe-0.19mass%Cr-0.14mass%Si-0.02mass%Ti with balance of Al) was processed by high-pressure torsion (HPT) under an applied pressure of 6 GPa for 1, 3 and 5 revolutions with a rotation speed of 1 rpm at room temperature. Vickers microhardness saturated to a level of 220 Hv after the HPT processing and the grain size was refined to 120 nm at the state of the hardness saturation. Tensile tests were conducted with initial strain rates from 2.0 × 10-4 to 2.0 × 10-2 s-1 at temperatures as 200 °C and 250 °C (equivalent to 0.52Tm and 0.57Tm, respectively, where Tm is the melting point of the alloy). The HPT-processed samples for 3 revolutions exhibited superplastic elongations of 640% and 510% at 250 °C with initial strain rates of 2.0 × 10-3 s-1 and 2.0 × 10-2 s-1, respectively.

X-Ray Analysis of High Pressure Torsion Induced Nanostructures in Ti and Ni

2006 ◽  
Vol 114 ◽  
pp. 329-336 ◽  
Author(s):  
A.R. Kilmametov ◽  
Ruslan Valiev ◽  
Igor V. Alexandrov
Keyword(s):  
High Pressure ◽  
High Pressure Torsion ◽  
Applied Pressure ◽  
Orientation Distribution ◽  
Nanocrystalline State ◽  
Cubic Symmetry ◽  
X Ray ◽  
Ω Phase ◽  
Commercially Pure ◽  
Pressure Phase

X-ray investigations revealed that the increase in the applied pressure during high pressure torsion (HPT) of commercially pure Ti leads not only to substructure refinement with an increase of the dislocation density and microstrain level but also to an α→ ω phase transition at room temperature. The coexistence of both α and ω phases, the latter known as a high pressure phase, in the ratio approximately of 1:3 has been obtained after removal of thehigh pressure. Texture analysis of electodeposited Ni after HPT discovered a new form of crystallite orientation distribution in the nanocrystalline state. A nearly random orientation crystallite distribution has been observed unlike the “traditional” case of a shear texture forming in cubic symmetry metals. The crystallographic texture data obtained were considered as experimental evidence of the changed plastic deformation mechanisms in nanocrystalline Ni produced by HPT.

scholarly journals Slippage during high-pressure torsion of commercially pure titanium and application of accumulative HPT to it

2022 ◽  
Vol 1213 (1) ◽  
pp. 012003
Author(s):  
D V Gunderov ◽  
A A Churakova ◽  
A V Sharafutdinov ◽  
V D Sitdikov ◽  
V V Astanin
Keyword(s):  
High Pressure ◽  
High Pressure Torsion ◽  
Pure Titanium ◽  
Phase Changes ◽  
Phase Content ◽  
Commercially Pure Titanium ◽  
Micro Hardness ◽  
Ω Phase ◽  
Commercially Pure ◽  
First Time

Abstract A new efficient method was used to find that in the case of high-pressure torsion of commercially pure titanium, accumulation of shear strain in Ti does not occur due to slippage of anvils. Despite this, micro-hardness increases as the number of turns n increases, and Ti structure is refined more intensively. High-pressure torsion is accompanied by a high-pressure ω-phase formation. However, the content of ω-phase changes non-monotonously with an increase in the number of turns. First, while number of turns is less than n=5, the ω-phase content reaches 50%. Upon further deformation, the ω-phase content decreases to 15% for n=20. A new accumulative high-pressure torsion method is applied to commercially pure titanium for the first time. Accumulative high-pressure torsion leads to the strongest transformation of the structure and an increase in hardness, since stronger real deformation occurs due to composition of compression and torsion strain cycles.

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