Contact Fracture Behaviors of Ti3SiC2 Synthesized by Hot Pressing Using TiCx and Si Powder Mixture

2005 ◽  
Vol 486-487 ◽  
pp. 217-220
Author(s):  
Sung Sic Hwang ◽  
Sang Whan Park ◽  
Seong Jai Cho ◽  
Dong Bok Lee
Keyword(s):  
Plastic Deformation ◽  
Fracture Behavior ◽  
Hertzian Contact ◽  
Coarse Grained ◽  
Vickers Indentation ◽  
Hertzian Indentation ◽  
Fine Grained ◽  
Fracture Behaviors ◽  
Hertzian Contact Stress ◽  
Contact Fracture

The contact fracture behaviors of fine-grained Ti3SiC2 and coarse-grained high purity Ti3SiC2 are examined by the Hertzian indentation and Vickers indentation technique. The Vickers hardness of bulk Ti3SiC2 is as low as 5.3~6.3 Gpa, and the Hertzian contact stress-strain curves for Ti3SiC2 deviate much from linearity, which resembles the fracture behavior of a ductile metal rather than a brittle ceramic. The contact damages by both Vickers indentation and Hertzian indentation reveal a fairly good plastic deformation nature of Ti3SiC2. Un-reacted TiCx in fine-grained Ti3SiC2 may impede the plastic deformation by slip along basal plan inside Ti3SiC2 grain, making Ti3SiC2 less plastic under loading.

Development of Ultra-Fine Grained Structure in an Al-5.4%Mg-0.5%Mn Alloy Processed by ECAP

2010 ◽  
Vol 667-669 ◽  
pp. 487-492
Author(s):  
Alla Kipelova ◽  
Ilya Nikulin ◽  
Sergey Malopheyev ◽  
Rustam Kaibyshev
Keyword(s):  
Plastic Deformation ◽  
Structure Formation ◽  
Equal Channel Angular Pressing ◽  
Microstructural Evolution ◽  
Coarse Grained ◽  
High Angle ◽  
Fine Grained ◽  
Angular Pressing ◽  
Fine Grained Structure ◽  
Zr Alloy

Microstructural changes during equal channel angular pressing (ECAP) at the temperatures of 250 and 300°C to the strains ~4, ~8 and ~12 were studied in a coarse-grained Al-5.4%Mg-0.5%Mn-0.1%Zr alloy. At a strain of ~4, the microstructural evolution is mainly characterized by the development of well-defined subgrains within interiors of initial grains and the formation of fine grains along original boundaries. Further straining leads to increase in the average misorientation angle, the fraction of high-angle grain boundaries and the fraction of new grains. However, only at 300°C, the plastic deformation to a strain of ~12 leads to the formation of almost uniform submicrocrystalline (SMC) grained structure with an average crystallites size of ~ 0.5 m. At 250°C, the microstructure remains non-uniform and consists of subgrains and new recrystallized grains. The mechanism of new SMC structure formation after ECAP is discussed.

scholarly journals Effect of ion nitriding by glow discharge on the physical and mechanical properties of the plastically deformed tool steel R6M5

2021 ◽  
Vol 2064 (1) ◽  
pp. 012052
Author(s):  
R K Vafin ◽  
A V Asylbaev ◽  
D V Mamontov ◽  
I D Sklizkov ◽  
G I Raab ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Glow Discharge ◽  
Tool Steel ◽  
Physical And Mechanical Properties ◽  
Coarse Grained ◽  
Steel R6m5 ◽  
Ion Nitriding ◽  
Fine Grained ◽  
Fine Grained Structure

Abstract This work is devoted to the study of the effect of the duration of ion nitriding by glow discharge on the physical and mechanical properties of tool steel with different initial structure. We used specimens of R6M5 tool steel with a coarse-grained structure obtained after annealing at a temperature of 850°C and with a fine-grained structure obtained after severe plastic deformation by torsion discharge. With an increase in the duration of ion nitriding, the thickness of the hardened layer and wear resistance increase. The combination of plastic deformation with ion nitriding by glow discharge increases the adsorption and diffusion rate of the saturating element due to the creation of a highly fragmented and disoriented fine-grained structure and contributed to reduction in processing time.

scholarly journals Interfacial Reactions and Fracture Behavior of Ti Alloy-Ag28Cu Brazing Joints: Influence of Titanium Alloy Composition

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 830 ◽  
Author(s):  
Joachim Gussone ◽  
Galina Kasperovich ◽  
Jan Haubrich ◽  
Guillermo Requena
Keyword(s):  
Titanium Alloys ◽  
Fracture Behavior ◽  
Titanium Substrate ◽  
Tensile Tests ◽  
Coarse Grained ◽  
X Ray ◽  
Fine Grained ◽  
Β Phase ◽  
Brazed Joints ◽  
Crack Paths

Brazing of titanium provides a joining technique suitable for the fabrication of highly-loaded aerospace components, but it still poses numerous challenges, such as the formation of brittle intermetallic interphases. This study of the interphase formation in brazed joints consisting of different titanium alloys (Ti-CP2, Ti-CP4, Ti-6Al-4V, Ti-6Al-2Mo-4Zr-2Sn) and Ag28Cu shows that complex reactions lead to the formation of various intermetallic phases including a Ti2Cu-TiCu boundary zone. The compositions of the titanium alloys influenced the particular microstructures, which have been characterized with various methods including synchrotron X-ray microtomography. Tensile tests evidence high ultimate tensile strengths that are, importantly, not directly limited by the strength of the brazing alloy. The strength of the Ti2Cu-TiCu phase boundary is significantly increased by the alloying elements in Ti-6Al-4V and Ti-6Al-2Mo-4Zr-2Sn and the crack paths change from boundary failure to transcrystalline fracture through TiCu as well as Ag-rich regions. Cu diffusion into the titanium substrate, leading to a coarse grained β-phase that transforms eutectoidally into a lamellar α-Ti + Ti2Cu structure during cooling, occurred in all systems except Ti-6Al-2Mo-4Zr-2Sn where Mo stabilized a fine grained microstructure and enabled the formation of a columnar TiCu structure.

Influence of Deformation on Precipitation Kinetics in Mg-Tb Alloy

2012 ◽  
Vol 322 ◽  
pp. 151-162 ◽  
Author(s):  
Oksana Melikhova ◽  
Jakub Čížek ◽  
Petr Hruška ◽  
Marián Vlček ◽  
Ivan Procházka ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Grain Boundaries ◽  
Positron Annihilation ◽  
High Pressure Torsion ◽  
Coarse Grained ◽  
Scanning Calorimetry ◽  
Fine Grained ◽  
Β Phase ◽  
Lower Temperature

Precipitation effects in age-hardenable Mg-13wt.%Tb alloy were investigated in this work. The solution treated alloy was subjected to isochronal annealing and decomposition of the supersaturated solid solution was investigated by positron annihilation spectroscopy combined with transmission electron microscopy, electrical resistometry, differential scanning calorimetry and microhardness measurements. Peak hardening was observed at 200°C due to precipitation of finely dispersed particles of β phase with the D019structure. Vacancy-like defects associated with β phase particles were detected by positron annihilation. At higher temperatures precipitation of β and subsequently β phase takes place. Formation of these phases lead to some additional hardening and introduces open volume defects at precipitate/matrix interfaces. To elucidate the effect of plastic deformation on the precipitation sequence we studied also a Mg-13wt.%Tb alloy with ultra fine grained structure prepared by high pressure torsion. In the ultra fine grained alloy precipitation of the β phase occurs at lower temperature compared to the coarse grained material and the peak hardening is shifted to a lower temperature as well. This effect can be explained by enhanced diffusivity of Mg and Tb atoms due to a dense network of grain boundaries and high density of dislocations introduced by severe plastic deformation. Moreover, dislocations and grain boundaries serve also as nucleation sites for precipitates. Hence, precipitation effects are accelerated in the alloy subjected to severe plastic deformation.

Development of Textured Coated Superconductor Substrate Tapes by Severe Plastic Deformation Processing

2010 ◽  
Vol 667-669 ◽  
pp. 1189-1194
Author(s):  
Pinaki Prasad Bhattacharjee ◽  
Nobuhiro Tsuji
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
High Purity ◽  
Cube Texture ◽  
Starting Material ◽  
Coarse Grained ◽  
Severe Plastic Deformation Processing ◽  
Processing Route ◽  
Fine Grained ◽  
Average Grain Size

An attempt has been made to fabricate highly cube textured ({001}<100>) polycrystalline nickel substrate tapes for coated superconductor applications using severe plastic deformation route. For this purpose high purity Ni (~99.97%) plates with widely different average grain size (28 µm or fine grained starting material and 650 µm or coarse grained starting material, respectively) are severely deformed by Accumulative Roll Bonding (ARB) up to an equivalent strain level of (εeq = 6.4) and annealed at various temperatures between 300° to 800°C for one hour. Upon annealing at different temperatures, the fine grained starting material developed a much stronger cube texture than the coarse grained starting material. By suitable annealing treatment near 100% cube textured tape could be obtained in the SPD processed fine grained nickel tapes having a predominantly low angle boundary network. The observed difference in the strength of cube texture in the two materials could be explained based on the oriented nucleation mechanism of formation of cube texture. The present results indicate that SPD processing route such as ARB is very effective in fabricating high purity Ni or Ni alloys intended for coated superconductor substrate applications.

Correlation between dislocation, grain boundary and interface of duplex SS in stress corrosion cracking(SCC)

1990 ◽  
Vol 48 (4) ◽  
pp. 928-929
Author(s):  
Wang Zheng-fang ◽  
Z.F. Wang
Keyword(s):  
Stainless Steel ◽  
Thermal Cycle ◽  
Secondary Phase ◽  
Corrosion Cracking ◽  
Coarse Grained ◽  
Test Environment ◽  
Fine Grained ◽  
Evaluation Test ◽  
Welding Thermal Cycle ◽  
Micro Analysis

The main purpose of this study highlights on the evaluation of chloride SCC resistance of the material,duplex stainless steel,OOCr18Ni5Mo3Si2 (18-5Mo) and its welded coarse grained zone(CGZ).18-5Mo is a dual phases (A+F) stainless steel with yield strength:512N/mm2 .The proportion of secondary Phase(A phase) accounts for 30-35% of the total with fine grained and homogeneously distributed A and F phases(Fig.1).After being welded by a specific welding thermal cycle to the material,i.e. Tmax=1350°C and t8/5=20s,microstructure may change from fine grained morphology to coarse grained morphology and from homogeneously distributed of A phase to a concentration of A phase(Fig.2).Meanwhile,the proportion of A phase reduced from 35% to 5-10°o.For this reason it is known as welded coarse grained zone(CGZ).In association with difference of microstructure between base metal and welded CGZ,so chloride SCC resistance also differ from each other.Test procedures:Constant load tensile test(CLTT) were performed for recording Esce-t curve by which corrosion cracking growth can be described, tf,fractured time,can also be recorded by the test which is taken as a electrochemical behavior and mechanical property for SCC resistance evaluation. Test environment:143°C boiling 42%MgCl2 solution is used.Besides, micro analysis were conducted with light microscopy(LM),SEM,TEM,and Auger energy spectrum(AES) so as to reveal the correlation between the data generated by the CLTT results and micro analysis.

scholarly journals Fracture behavior of twin induced ultra-fine grained ZK61 magnesium alloy under high strain rate compression

2019 ◽  
Vol 8 (4) ◽  
pp. 3475-3486 ◽  
Author(s):  
Abdul Malik ◽  
Wang Yangwei ◽  
Cheng Huanwu ◽  
Muhammad Abubaker Khan ◽  
Faisal Nazeer ◽  
...  
Keyword(s):  
Magnesium Alloy ◽  
High Strain Rate ◽  
Strain Rate ◽  
Fracture Behavior ◽  
High Strain ◽  
Fine Grained ◽  
Strain Rate Compression

scholarly journals Balanced Sparsity for Efficient DNN Inference on GPU

2019 ◽  
Vol 33 ◽  
pp. 5676-5683 ◽  
Author(s):  
Zhuliang Yao ◽  
Shijie Cao ◽  
Wencong Xiao ◽  
Chen Zhang ◽  
Lanshun Nie
Keyword(s):  
Deep Neural Networks ◽  
General Purpose ◽  
Coarse Grained ◽  
Efficient Computation ◽  
Model Accuracy ◽  
Sparse Model ◽  
Model Inference ◽  
Fine Grained ◽  
Practical Inference ◽  
Speed Up

In trained deep neural networks, unstructured pruning can reduce redundant weights to lower storage cost. However, it requires the customization of hardwares to speed up practical inference. Another trend accelerates sparse model inference on general-purpose hardwares by adopting coarse-grained sparsity to prune or regularize consecutive weights for efficient computation. But this method often sacrifices model accuracy. In this paper, we propose a novel fine-grained sparsity approach, Balanced Sparsity, to achieve high model accuracy with commercial hardwares efficiently. Our approach adapts to high parallelism property of GPU, showing incredible potential for sparsity in the widely deployment of deep learning services. Experiment results show that Balanced Sparsity achieves up to 3.1x practical speedup for model inference on GPU, while retains the same high model accuracy as finegrained sparsity.

scholarly journals Submarine lava deltas of the 2018 eruption of Kīlauea volcano

2021 ◽  
Vol 83 (4) ◽  
Author(s):  
S. Adam Soule ◽  
Michael Zoeller ◽  
Carolyn Parcheta
Keyword(s):  
Grain Size ◽  
Pore Pressure ◽  
Mechanistic Model ◽  
Large Fraction ◽  
Volcanic Hazards ◽  
Lava Flows ◽  
Coarse Grained ◽  
Fine Grained ◽  
Fine Grain ◽  
Delta Formation

AbstractHawaiian and other ocean island lava flows that reach the coastline can deposit significant volumes of lava in submarine deltas. The catastrophic collapse of these deltas represents one of the most significant, but least predictable, volcanic hazards at ocean islands. The volume of lava deposited below sea level in delta-forming eruptions and the mechanisms of delta construction and destruction are rarely documented. Here, we report on bathymetric surveys and ROV observations following the Kīlauea 2018 eruption that, along with a comparison to the deltas formed at Pu‘u ‘Ō‘ō over the past decade, provide new insight into delta formation. Bathymetric differencing reveals that the 2018 deltas contain more than half of the total volume of lava erupted. In addition, we find that the 2018 deltas are comprised largely of coarse-grained volcanic breccias and intact lava flows, which contrast with those at Pu‘u ‘Ō‘ō that contain a large fraction of fine-grained hyaloclastite. We attribute this difference to less efficient fragmentation of the 2018 ‘a‘ā flows leading to fragmentation by collapse rather than hydrovolcanic explosion. We suggest a mechanistic model where the characteristic grain size influences the form and stability of the delta with fine grain size deltas (Pu‘u ‘Ō‘ō) experiencing larger landslides with greater run-out supported by increased pore pressure and with coarse grain size deltas (Kīlauea 2018) experiencing smaller landslides that quickly stop as the pore pressure rapidly dissipates. This difference, if validated for other lava deltas, would provide a means to assess potential delta stability in future eruptions.

scholarly journals A cooperative DDoS attack detection scheme based on entropy and ensemble learning in SDN

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Shanshan Yu ◽  
Jicheng Zhang ◽  
Ju Liu ◽  
Xiaoqing Zhang ◽  
Yafeng Li ◽  
...  
Keyword(s):  
Ensemble Learning ◽  
Denial Of Service ◽  
Attack Detection ◽  
Coarse Grained ◽  
Communication Overhead ◽  
Detection Scheme ◽  
Fine Grained ◽  
Ddos Attack ◽  
Network Status ◽  
Ddos Attack Detection

AbstractIn order to solve the problem of distributed denial of service (DDoS) attack detection in software-defined network, we proposed a cooperative DDoS attack detection scheme based on entropy and ensemble learning. This method sets up a coarse-grained preliminary detection module based on entropy in the edge switch to monitor the network status in real time and report to the controller if any abnormality is found. Simultaneously, a fine-grained precise attack detection module is designed in the controller, and a ensemble learning-based algorithm is utilized to further identify abnormal traffic accurately. In this framework, the idle computing capability of edge switches is fully utilized with the design idea of edge computing to offload part of the detection task from the control plane to the data plane innovatively. Simulation results of two common DDoS attack methods, ICMP and SYN, show that the system can effectively detect DDoS attacks and greatly reduce the southbound communication overhead and the burden of the controller as well as the detection delay of the attacks.

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