scholarly journals Rapid heating induced ultrahigh stability of nanograined copper

2020 ◽  
Vol 6 (17) ◽  
pp. eaaz8003 ◽  
Author(s):  
X.Y. Li ◽  
X. Zhou ◽  
K. Lu
Keyword(s):  
Grain Boundary ◽  
Critical Size ◽  
Rapid Heating ◽  
Coarse Grained ◽  
Recrystallization Temperature ◽  
Mechanical Instability ◽  
Thermally Induced ◽  
Alternative Approach ◽  
Boundary Relaxation ◽  
Pure Cu

Inherent thermal and mechanical instability of nanograined materials bottlenecks their processing and technological applications. In addition to the traditional stabilization strategy, which is based on alloying, grain boundary relaxation was recently found to be effective in stabilizing nanograined pure metals. Grain boundary relaxation can be induced by deforming very fine nanograins below a critical size, typically several tens of nanometers. Here, we found that rapid heating may trigger intensive boundary relaxation of pure Cu nanograins with sizes up to submicrometers, a length scale with notable instability in metals. The rapidly heated Cu nanograins remain stable at temperatures as high as 0.6 Tm (melting point), even higher than the recrystallization temperature of deformed coarse-grained Cu. The thermally induced grain boundary relaxation originating from the generation of high-density nanotwins offers an alternative approach to stabilizing nanostructured materials.

Grain boundary relaxation in fine-grained magnesium solid solutions

2011 ◽  
Vol 91 (32) ◽  
pp. 4158-4171 ◽  
Author(s):  
Hiroyuki Watanabe ◽  
Akira Owashi ◽  
Tokuteru Uesugi ◽  
Yorinobu Takigawa ◽  
Kenji Higashi
Keyword(s):  
Grain Boundary ◽  
Solid Solutions ◽  
Fine Grained ◽  
Boundary Relaxation

Influence of a weak pulsed magnetic field on grain-boundary relaxation in aluminum

1999 ◽  
Vol 41 (11) ◽  
pp. 1821-1823
Author(s):  
O. I. Datsko ◽  
V. I. Alekseenko ◽  
A. L. Brusova
Keyword(s):  
Magnetic Field ◽  
Grain Boundary ◽  
Pulsed Magnetic Field ◽  
Boundary Relaxation

Modern Models of Grain Boundary Diffusion

2011 ◽  
Vol 312-315 ◽  
pp. 1116-1125
Author(s):  
Vladimir V. Popov
Keyword(s):  
Plastic Deformation ◽  
Grain Boundary ◽  
Severe Plastic Deformation ◽  
Nanocrystalline Materials ◽  
Boundary Diffusion ◽  
Grain Boundary Diffusion ◽  
Coarse Grained ◽  
Gas Condensation ◽  
Non Equilibrium

Recent models of grain-boundary diffusion are briefly reviewed. Models of diffusion along equilibrium boundaries of recrystallization origin in coarse-grained materials and along non-equilibrium boundaries in nanocrystalline materials obtained by gas condensation and compacting or by severe plastic deformation are considered separately.

Generation and Propagation of Thermally Induced Acoustic Waves in Supercritical Fluids: Numerical and Experimental Results

2010 ◽  
Author(s):  
Bakhtier Farouk ◽  
Zhieheng Lei
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Supercritical Fluid ◽  
Supercritical Fluids ◽  
Acoustic Waves ◽  
Rapid Heating ◽  
Time Dependent ◽  
Cylindrical Chamber ◽  
Thermally Induced ◽  
Supercritical Carbon

The behavior of thermally induced acoustic waves generated by the rapid heating of a bounding solid wall in a closed cylindrical chamber filled with supercritical carbon dioxide is investigated numerically and experimentally. A time-dependent one-dimensional problem is considered for the numerical simulations where the supercritical fluid is contained between two parallel plates. The NIST Reference Database 12 is used to obtain the property relations for supercritical carbon dioxide. The thermally induced pressure (acoustic) waves undergo repeated reflections at the two confining walls and gradually dissipate. The numerically predicted temperature of the bulk supercritical fluid is found to increase homogeneously (the so called piston effect) within the domain. The details of generation, propagation and dissipation of thermally induced acoustic waves in supercritical fluids are presented under different heating rates. In the experiments, a resistance-capacitance circuit is used to generate a rapid temperature increase in a thin metal foil located at one end of a closed cylindrical chamber. The time-dependent pressure variation in the chamber and the temperature history at the foil are recorded by a fast response measurement system. Both the experimental and numerical studies predict similar pressure wave shapes and profiles due to rapid heating of a wall.

Superplasticity and Grain Boundary Relaxation in High-Carbon Tool Steel

1987 ◽  
pp. 1343-1346
Author(s):  
Ch. Kortensky ◽  
N. Mitev ◽  
I. Spirov ◽  
N. Dyulgerov
Keyword(s):  
Grain Boundary ◽  
Tool Steel ◽  
High Carbon ◽  
Boundary Relaxation

Creep Property of Boron Added 9Cr Heat Resistant Steels after Welding

2018 ◽  
Vol 941 ◽  
pp. 340-345
Author(s):  
Tetsuya Matsunaga ◽  
Maaouia Souissi ◽  
Ryoji Sahara ◽  
Hiromichi Hongo ◽  
Masaaki Tabuchi ◽  
...  
Keyword(s):  
High Temperature ◽  
Grain Boundary ◽  
Rapid Heating ◽  
Boundary Migration ◽  
Creep Property ◽  
Creep Tests ◽  
Precipitate Morphology ◽  
Premature Failure ◽  
Heat Resistant ◽  
Type Iv

Although welding results in premature failure by type IV fracture under high temperature creep conditions, the alloy design of light elements such as boron addition and nitrogen reduction enhances the creep lifetime of 9Cr heat resistant steel. In particular, the simulated heat affected zone (SHAZ) sample of new 9Cr steel (called TA steel) shows about 10 times longer creep lifetime than that of the standard Gr. 91 steel. The welded TA steel is thus expected to exhibit good creep properties because its SHAZ sample has coarser grains and suppresses type IV fracture. The preservation of base metal’s microstructure after welding results from the precipitate morphology, such as high grain boundary coverage by precipitates and low amount of MX being nucleation sites of ferrite grains during the a-g phase transformation. In addition, the increase of stability of M23C6 affects high pinning pressure toward grain boundary migration upon rapid heating during welding. First-principles calculations confirm the increased stability when boron is absorbed by M23C6. Moreover, the calculations reveals that boron decreases the coherency between matrix and M23C6, suppressing grain coarsening during creep tests in TA steel. It is concluded that the increased microstructural stability during welding and long high temperature exposure generates the elongated creep lifetime in welded TA steel including about 0.01 wt% boron and less than 0.01 wt% nitrogen.

scholarly journals Rapid Thermal Characterization of Graphene Oxide—Nanocalorimetry as a Pathway for Novel Insights in Tribology

Lubricants ◽  
2019 ◽  
Vol 7 (11) ◽  
pp. 96
Author(s):  
Karsten Woll ◽  
Tobias Neuhauser ◽  
Camilo Acuña ◽  
Donovan Diaz-Droguett ◽  
Andreas Rosenkranz
Keyword(s):  
Graphene Oxide ◽  
Rapid Heating ◽  
High Sensitivity ◽  
Thermal Characterization ◽  
Solid Lubricants ◽  
Model Material ◽  
Thermally Induced ◽  
Exothermic Reactions ◽  
Sliding Motion

The use of solid lubricants such as graphene, graphene oxide, and other nanoparticles have gained notable attention in the tribological community to reduce friction and wear thus aiming at improved energy efficiency and sustainability. Tribological experiments unify rather extreme conditions such as high contact pressures, small contact areas, relative sliding motion, and rapid heating. This combination leads to mechanically- and/or thermally induced chemical, structural and microstructural modifications of the lubricating nanoparticles during rubbing thus altering their material’s properties. Due to the high sensitivity, we propose nanocalorimetry as the method of choice to shed more light on the thermally-induced processes and changes. As a model material for solid lubricants, we explore the transitions of graphene oxide under heating with 1000 °C/s up to 600 °C using quasi-adiabatic nanocalorimetry. We identify a strong exothermic runaway reaction at 317 °C. This runaway is preceded by exothermic reactions between 75–125 °C, which are correlated with the release of intercalated species and the formation of CO and CO2.

Anomalous Effect of Strain Rate on the Tensile Elongation of Coarse-Grained Pure Iron with Grain Boundary Micro-Voids

2011 ◽  
Vol 214 ◽  
pp. 334-338 ◽  
Author(s):  
Xin Ming Cao ◽  
Qi Qiang Duan ◽  
Xiao Wu Li
Keyword(s):  
Grain Boundary ◽  
Strain Rate ◽  
Pure Iron ◽  
Tensile Elongation ◽  
Total Elongation ◽  
Coarse Grained ◽  
Strength Increase ◽  
Lower Yield Stress ◽  
Anomalous Effect ◽  
Tensile Direction

The plastic deformation and damage behavior of coarse-grained commercially pure iron containing grain boundary micro-voids were investigated at room temperature with different strain rates ranging from 1.0×10-5s-1 to 1.0×10-2s-1 under uniaxial tension. It is found that, with increasing strain rate, the lower yield stress and ultimate tensile strength increase normally, and abnormally the elongation increases as well. By comparison with the similar cases of other materials, the present phenomenon of anomalous strain rate effect on elongation is thought to be related to the pre-existence of GB micro-voids in the raw CP iron material. The extending deformation of GB micro-voids towards the tensile direction would contribute more to the total elongation, as the strain rate increases; this should be the most possible reason for the anomalous strain-rate dependence of elongation.

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