Synchroshear Versus Conventional Shear Mechanisms in Transitionmetal Disilicides with the C40 Structure

1999 ◽  
Vol 578 ◽  
Author(s):  
H. Inui ◽  
M. Yamaguchi
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Plastic Flow ◽  
Deformation Mechanism ◽  
Deformation Behavior ◽  
Basal Slip ◽  
Room Temperature ◽  
Onset Temperature ◽  
Factors Affecting ◽  
Temperature Group

AbstractThe deformation behavior of (0001) <1210> basal slip in single crystals of five different transitionmetal disilicides with the C40 structure has been investigated in the temperature range from room temperature to 1500°C in compression. These disilicides are found to be classified into two groups depending on the onset temperature for plastic flow. The low-temperature group, which consists of VSi2, NbSi2 and TaSi2, exhibits the onset temperature for plastic flow around 0.3 T/Tm (melting temperature) and deforms by a conventional shear mechanism. In contrast, the high temperature group, which consists of CrSi2 and Mo(Si,Al)2, exhibits the onset temperature around 0.6T/Tm and deforms by a synchroshear mechanism. Factors affecting the deformation mechanism in these C40 disilicides are discussed in terms of directionality of atomic bonding and the relative stability of the C40 phase with respect to the C11b phase.

High Temperature Deformation Mechanism Maps of NiAl

2004 ◽  
Vol 449-452 ◽  
pp. 57-60
Author(s):  
I.G. Lee ◽  
A.K. Ghosh
Keyword(s):  
High Temperature ◽  
Strain Rate ◽  
Deformation Mechanism ◽  
Calculation Method ◽  
Deformation Behavior ◽  
Tensile Tests ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Grain Sizes ◽  
Temperature Strain

In order to analyze high temperature deformation behavior of NiAl alloys, deformation maps were constructed for stoichiometric NiAl materials with grain sizes of 4 and 200 µm. Relevant constitute equations and calculation method will be described in this paper. These maps are particularly useful in identifying the location of testing domains, such as creep and tensile tests, in relation to the stress-temperature-strain rate domains experienced by NiAl.

Search for High Damping Metallic Glasses

2006 ◽  
Vol 319 ◽  
pp. 151-156 ◽  
Author(s):  
Y. Hiki ◽  
M. Tanahashi ◽  
Shin Takeuchi
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Internal Friction ◽  
Metallic Glass ◽  
Room Temperature ◽  
Temperature Stability ◽  
Temperature Peak ◽  
High Temperature Side ◽  
Side Slope ◽  
Temperature Side

In a hydrogen-doped metallic glass, there appear low-temperature and high-temperature internal friction peaks respectively associated with a point-defect relaxation and the crystallization. The high-temperature-side slope of low-temperature peak and also the low-temperature-side slope of high-temperature peak enhance the background internal friction near the room temperature. A hydrogen-doped Mg-base metallic glass was proposed as a high-damping material to be used near and somewhat above the room temperature. Stability of the high damping was also checked.

Plastic Deformation of Mo(Si,Al)2 Single Crystals with the C40 Structure

1996 ◽  
Vol 460 ◽  
Author(s):  
M. Moriwaki ◽  
K. Ito ◽  
H. Inui ◽  
M. Yamaguchi
Keyword(s):  
Single Crystals ◽  
Deformation Behavior ◽  
Basal Slip ◽  
Room Temperature ◽  
Slip Systems ◽  
Temperature Range ◽  
Al Content ◽  
Partial Dislocations ◽  
Increasing Temperature ◽  
Critical Resolved Shear Stress

ABSTRACTThe deformation behavior of single crystals of Mo(Si,Al)2 with the C40 structure has been studied as a function of crystal orientation and Al content in the temperature range from room temperature to 1500°C in compression. Plastic flow is possible only above 1100°C for orientations where slip along <1120> on (0001) is operative and no other slip systems are observed over whole temperature range investigated. The critical resolved shear stress for basal slip decreases rapidly with increasing temperature and the Schmid law is valid. Basal slip appears to occur through a synchroshear mechanism, in which a-dislocations (b=1/3<1120>) dissociate into two synchro-partial dislocations with the identical Burgers vector(b*1/6<1120>) and each synchro-partial further dissociates into two partials on two adjacent planes.

Low Temperature Co-fired Ceramics Processing Parameters Governing the Performance of Miniaturized Force Sensors

2012 ◽  
Vol 2012 (CICMT) ◽  
pp. 000411-000416
Author(s):  
Michael Weilguni ◽  
Walter Smetana ◽  
Goran Radosavljevic ◽  
Johann Nicolics ◽  
Werner Goebl ◽  
...  
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Room Temperature ◽  
Processing Parameters ◽  
Gauge Factor ◽  
Force Sensors ◽  
Stabilized Zirconia ◽  
Temperature Coefficient Of Resistance ◽  
Microscope Images ◽  
Resistive Thick Film

For the development of miniaturized force sensors, built up in ceramics technology with piezo-resistive principle, the compatibility of the piezo-resistive thick-film paste with the substrate and termination paste has to be verified. This paper deals with the compatibility of the ESL 3414-A piezo-resistive paste on HTCC (high temperature co-fired ceramics) substrates (alumina as reference and the partially stabilized zirconia tape ESL 42013-A) as well as on LTCC (low temperature co-fired ceramics) substrates (Heraeus AHT01-005, AHT08-047, CT707; and CeramTec GC) under different manufacturing conditions. The sheet resistance at room temperature, the longitudinal gauge factor at room temperature and the temperature coefficient of resistance have been measured. The results are compared with microscope images showing cracks in distinct cases. Finally, the compatibility and thus applicability of the ESL 3414-A on the investigated substrates is evaluated.

STEPPED-COMBUSTION 14C DATING IN LOESS-PALEOSOL SEDIMENT

Radiocarbon ◽  
2020 ◽  
Vol 62 (5) ◽  
pp. 1209-1220
Author(s):  
Peng Cheng ◽  
Yunchong Fu
Keyword(s):  
Climate Change ◽  
High Temperature ◽  
Low Temperature ◽  
Organic Carbon ◽  
Room Temperature ◽  
14C Dating

ABSTRACTIn this study, low temperature (room temperature, 400°C LT) and high temperature (400–900°C HT) of bulk organic carbon samples were dated from two loess and paleosol profiles. The results showed that radiocarbon (14C) dates of the LT were younger than HT fractions, indicating effect of younger contamination from overlying layers. The δ13C variation of the HT fraction appears to respond much more sensitively to climate change, and 14C ages of HT fraction can produce reasonable 14C ages from a younger layer, but it is very difficult to obtain reliable 14C ages from older layer as a result of uncomplete removal of young carbon.

scholarly journals Study on Wear and Fatigue Performance of Two Types of High-Speed Railway Wheel Materials at Different Ambient Temperatures

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1152
Author(s):  
Lei MA ◽  
Wenjian WANG ◽  
Jun GUO ◽  
Qiyue LIU
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
High Speed ◽  
Room Temperature ◽  
Lamellar Spacing ◽  
Wear Loss ◽  
High Speed Railway ◽  
Railway Wheel ◽  
Ambient Temperatures ◽  
Railway Wheels

The wear and fatigue behaviors of two newly developed types of high-speed railway wheel materials (named D1 and D2) were studied using the WR-1 wheel/rail rolling–sliding wear simulation device at high temperature (50 °C), room temperature (20 °C), and low temperature (−30 °C). The results showed that wear loss, surface hardening, and fatigue damage of the wheel and rail materials at high temperature (50 °C) and low temperature (−30 °C) were greater than at room temperature, showing the highest values at low temperature. With high Si and V content refining the pearlite lamellar spacing, D2 presented better resistance to wear and fatigue than D1. Generally, D2 wheel material appears more suitable for high-speed railway wheels.

Formation, Characterization, and Wear Behavior of Aluminide Coating on Mirrax® ESR Steel by Low-Temperature Aluminizing Process

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Tuba Yener ◽  
Azmi Erdogan ◽  
Mustafa Sabri Gök ◽  
Sakin Zeytin
Keyword(s):  
Wear Resistance ◽  
High Temperature ◽  
Low Temperature ◽  
Room Temperature ◽  
Wear Behavior ◽  
Aluminide Coating ◽  
Pure Aluminum ◽  
Dry Sliding Wear ◽  
Thickness Variation ◽  
Wear Tests

Abstract The aim of this study was to investigate the effect of low-temperature aluminizing process on the microstructure and dry sliding wear properties of Mirrax steel. Low-temperature aluminizing process was applied on Mirrax steel at 600, 650, and 700 °C for 2, 4, and 6 h. The packs for the process were prepared using pure aluminum powder as aluminum deposition source. Ammonium chloride NH4Cl and Seydisehir Al2O3 powder were used as the activator and the inert filler, respectively. Scanning electron microscope (SEM)/energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) analysis were applied for characterization of the coating surfaces. The through-thickness variation in the layer microstructure was determined and it was found to vary between 1 µm and 45 µm which increased with higher process temperature and time. After the deposition process, the coating layer hardness increased to 1000 HVN, whereas the hardness of the matrix was 250 HVN. The wear tests were performed using a ball-on-disc tribometer under 5 N load at room temperature and 500 °C on aluminized and untreated Mirrax steel. In both room temperature and high-temperature wear tests, it was determined that the aluminizing process increased the wear resistance of Mirrax steel. Increasing aluminizing time and temperature also increased the wear resistance. The uncoated and thin-coated samples generally exhibited wear in the form of plastic deformation and adhesion related ruptures. A high degree of tribological layer was observed on the wear trace on samples with high coating thickness, especially in high-temperature tests. Therefore, the volume losses in these samples were induced by fatigue crack formation and delamination.

Influence of Al-Cu-Mn-Fe-Ti Alloy Composition and Production Parameters of Extruded Semi-Finished Products on their Structure and Mechanical Properties

2017 ◽  
Vol 265 ◽  
pp. 456-462 ◽  
Author(s):  
P.L. Reznik ◽  
Mikhail Lobanov
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Thermal Treatment ◽  
Low Temperature ◽  
Room Temperature ◽  
High Temperature Strength ◽  
Ti Alloy ◽  
Low Temperature Annealing ◽  
Annealing Conditions ◽  
Concentration Changes

Studies have been conducted as to the effect of Cu, Mn, Fe concentration changes in Al-Cu-Mn-Fe-Ti alloy, the conditions of thermal and deformational treatment of ingots and extruded rods 40 mm in diameter on the microstructure, phase composition and mechanical properties. It has been determined that changing Al-6.3Cu-0.3Mn-0.17Fe-0.15Ti alloy to Al-6.5Cu-0.7Mn-0.11Fe-0.15Ti causes an increase in the strength characteristics of extruded rods at the room temperature both after molding and in tempered and aged conditions, irrespective of the conditions of thermal treatment of the initial ingot (low-temperature annealing 420 °С for 2 h, or high-temperature annealing at 530 °С for 12 h). Increasing the extruding temperature from 330 to 480 °С, along with increasing Cu, Mn and decreasing Fe in the alloy Al-Cu-Mn-Ti, is accompanied by the increased level of ultimate strength in a quenched condition by 25% to 410 MPa, irrespective of the annealing conditions of the original ingot. An opportunity to apply the Al-6.3Cu-0.3Mn-0.17Fe-0.15Ti alloy with low-temperature annealing at 420 °С for 2 h and the molding temperature of 330 °С has been found to produce rods where, in the condition of full thermal treatment (tempering at 535 °С + aging at 200 °С for 8 hours), a structure is formed that ensures satisfactory characteristics of high temperature strength by resisting to fracture for more than 100 hours at 300 °С and 70 MPa.

Effect of Temperature on Crater Formation and Ejecta Composition in Aluminum Alloy Targets

2012 ◽  
Vol 706-709 ◽  
pp. 768-773
Author(s):  
Masahiro Nishida ◽  
Koichi Hayashi ◽  
Junichi Nakagawa ◽  
Yoshitaka Ito
Keyword(s):  
Aluminum Alloy ◽  
High Temperature ◽  
Low Temperature ◽  
Room Temperature ◽  
Effect Of Temperature ◽  
Crater Formation ◽  
Influence Of Temperature ◽  
Gas Gun ◽  
Influence Of Temperature On ◽  
Increasing Temperature

The influence of temperature on crater formation and ejecta composition in thick aluminum alloy targets were investigated for impact velocities ranging from approximately 1.5 to 3.5 km/s using a two-stage light-gas gun. The diameter and depth of the crater increased with increasing temperature. The ejecta size at low temperature was slightly smaller than that at high temperature and room temperature. Temperature did not affect the size ratio of ejecta. The scatter diameter of the ejecta at high temperature was slightly smaller than those at low and room temperatures.

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