Structure and Properties of Ultrafine-Grained Cu-Cr Alloys after High Pressure Torsion

2010 ◽  
Vol 667-669 ◽  
pp. 301-306 ◽  
Author(s):  
D.V. Shangina ◽  
N.R. Bochvar ◽  
Sergey V. Dobatkin
Keyword(s):  
Thermal Stability ◽  
Chromium Content ◽  
High Pressure Torsion ◽  
Softening Temperature ◽  
Initial State ◽  
Resistivity Measurements ◽  
Chromium Alloys ◽  
Ultrafine Grained ◽  
The Stability ◽  
Thermal Stability Of

The effect of chromium content (0.75, 9.85, 27%) and initial state on the thermal stability of copper-chromium alloys after severe plastic deformation has been studied by microhardness and electrical resistivity measurements. The stability of the structures is established to depend on the initial state of the alloys and on the content of chromium phase. In the low-alloy bronze, quenching before HPT substantially increases the thermal stability of the alloy relative to that observed after annealing. The softening temperature increases with increasing chromium phase content and reaches 450°C for the alloy with 27% Cr.

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.

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 Microstructure and Properties of Cu-0.5Cr-0.2Zr Alloy Subjected to ECAP and Cold Rolling

2018 ◽  
Vol 385 ◽  
pp. 278-283
Author(s):  
Elena Sarkeeva ◽  
Marina M. Abramova ◽  
Wei Wei
Keyword(s):  
Thermal Stability ◽  
Electrical Conductivity ◽  
Plastic Deformation ◽  
Copper Alloys ◽  
Physical And Mechanical Properties ◽  
Initial State ◽  
Microstructure And Properties ◽  
Mechanical And Electrical Properties ◽  
Ultrafine Grained ◽  
Thermal Stability Of

Copper and copper alloys are widely used in engineering as structural materials because they have high electrical and thermal conductivity. In connection with the rapid growth of industry, special requirements are imposed on these materials, that is, they must withstand the contact mechanical loads without significant plastic deformation at elevated temperature and have stable high physical and mechanical properties. To improve the combination of strength, electrical conductivity, thermal stability, and wear resistance, low-alloyed Cu-Cr-Zr copper alloys have been subject to severe plastic deformation and aging. It the same time the analysis of the termo-stability of the formed ultrafine grained microstructure and properties is a topic task. In this work, a Cu-0.5Cr-0.2Zr (wt. %) alloy was quenched to form solid solution, equal channel angular pressed and cold rolled with following aging. The microstructure was studied, mechanical and electrical properties were also analyzed. The results showed that the ultimate strength of the Cu-Cr-Zr alloy increases with the degree of deformation at room temperature up to 630 MPa. Heat treatment at 450 ° C for 1 hour led to the precipitation of Cr and Cu5Zr particles, which increases the strength up to 660 MPa, which is 2.5 times greater than the initial state. At the same time, sufficient electrical conductivity of 70% IACS is maintained. The thermal stability of the microstructure and properties of the alloy are investigated. The reinforced alloy maintains stable the microstructure and microhardness at 450 ° C for at least 5 hours. The change in microhardness is no more than 10%. That is in agreement with the requirements of industry.

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

Intrinsic Thermal Stability of Anisotropic Thin-Film Superconductors

1990 ◽  
Vol 112 (1) ◽  
pp. 10-15 ◽  
Author(s):  
M. I. Flik ◽  
C. L. Tien
Keyword(s):  
Thin Film ◽  
Thermal Stability ◽  
Stability Criterion ◽  
High Temperature Superconductors ◽  
Stability Criteria ◽  
Anisotropic Thermal Conductivity ◽  
Operating Current ◽  
Released Energy ◽  
The Stability ◽  
Thermal Stability Of

Intrinsic thermal stability denotes a situation where a superconductor can carry the operating current without resistance at all times after the occurrence of a localized release of thermal energy. This novel stability criterion is different from the cryogenic stability criteria for magnets and has particular relevance to thin-film superconductors. Crystals of ceramic high-temperature superconductors are likely to exhibit anisotropic thermal conductivity. The resultant anisotropy of highly oriented films of superconductors greatly influences their thermal stability. This work presents an analysis for the maximum operating current density that ensures intrinsic stability. The stability criterion depends on the amount of released energy, the Biot number, the aspect ratio, and the ratio of the thermal conductivities in the plane of the film and normal to it.

scholarly journals Thermal Stability of Residual Stresses in Differently Deep Rolled Surface Layers of Steel SAE 1045

2021 ◽  
Author(s):  
Stephanie Saalfeld ◽  
Thomas Wegener ◽  
Berthold Scholtes ◽  
Thomas Niendorf
Keyword(s):  
Thermal Stability ◽  
Elevated Temperature ◽  
Residual Stresses ◽  
Elevated Temperatures ◽  
Fatigue Behavior ◽  
Decisive Role ◽  
Deep Rolling ◽  
Material Conditions ◽  
The Stability ◽  
Thermal Stability Of

AbstractThe stability of compressive residual stresses generated by deep rolling plays a decisive role on the fatigue behavior of specimens and components, respectively. In this regard, deep rolling at elevated temperature has proven to be very effective in stabilizing residual stresses when fatigue analysis is conducted at ambient temperature. However, since residual stresses can be affected not only by plastic deformation but also when thermal energy is provided, it is necessary to analyze the influence of temperature and time on the relaxation behavior of residual stresses at elevated temperature. To evaluate the effect of deep rolling at elevated temperatures on stability limits under thermal as well as combined thermo-mechanical loads, the present work introduces and discusses the results of investigations on the thermal stability of residual stresses in differently deep rolled material conditions of the steel SAE 1045.

scholarly journals Change in the stability of goat milk and cow milk due to pH and heat

2021 ◽  
Vol 233 ◽  
pp. 02046
Author(s):  
Xiaoxue Fan ◽  
Ming Cheng ◽  
Xiaoning Zhang ◽  
Cunfang Wang ◽  
Hua Jiang
Keyword(s):  
Thermal Stability ◽  
Milk Production ◽  
Ph Value ◽  
Goat Milk ◽  
Cow Milk ◽  
Type B ◽  
Fresh Milk ◽  
Ph Conditions ◽  
The Stability ◽  
Thermal Stability Of

This paper aimed to evaluate the changes in the thermal stability of goat milk, cow milk and homogenized milk under different pH conditions. The results showed that goat milk was of type B milk, and the thermal stability were positively correlated with the pH value. But cow milk was of type A milk, the most stable pH of fresh milk was 6.9, while it was 6.7 for homogenized cow milk. Compared with cow milk, the acidification of goat milk was stronger due to heat. Therefore, in the process of milk production, the germicidal heating conditions of two different milk sources should be determined according to their thermal stability.

Thermal Stability of Strained InGaAs/GaAs Single Quantum Wells

1989 ◽  
Vol 160 ◽  
Author(s):  
B. Elman ◽  
Emil S. Koteles ◽  
P. Melman ◽  
C.A. Armiento ◽  
C. Jagannath
Keyword(s):  
Thermal Stability ◽  
Quantum Wells ◽  
Molecular Beam ◽  
Critical Thickness ◽  
Single Quantum ◽  
Furnace Annealing ◽  
Low Dislocation Density ◽  
The Stability ◽  
Thermal Stability Of ◽  
Low Temperature Photoluminescence

AbstractWe present a study of the structural stability of InGaAs/GaAs strained single quantum wells (SQW) grown with a variety of indium compositions and with well widths close to critical thickness values. The samples were grown by molecular beam epitaxy and were subjected to furnace annealing as well as ion implantation followed by rapid thermal annealing. Changes in low temperature photoluminescence linewidths were used to evaluate the stability of strained SQWs. We observed both strain relief, in wide SQWs and strain recovery, in higher indium composition narrow quantum wells which were partially relaxed (low dislocation density) as-grown.

Thermal Stability of Magnetic Properties in Dehydrogenated Triarylmethane Resins

1989 ◽  
Vol 173 ◽  
Author(s):  
Michiya Otani ◽  
Sugio Otani
Keyword(s):  
Thermal Stability ◽  
Magnetic Properties ◽  
Magnetic Property ◽  
Room Temperature ◽  
Permanent Magnets ◽  
Elevated Temperatures ◽  
Mechanical Response ◽  
The Stability ◽  
Thermal Stability Of

ABSTRACTThe stability of the magnetic properties of dehydrogenated triaryl-methane resins was investigated both at room temperature and at elevated temperatures. A magnetic property different from that reported in a previous paper was found in the course of studying the reproducibility of synthesis. This new property was examined through a mechanical response of the resins to a set of permanent magnets.

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