scholarly journals Деформация памяти формы и микрорельеф поверхности монокристаллов сплавов Ni-Fe-Ga-Co и Cu-Al-Ni

2019 ◽  
Vol 45 (5) ◽  
pp. 27
Author(s):  
Ю.Г. Носов ◽  
А.В. Солдатов ◽  
В.М. Крымов ◽  
С.А. Пульнев ◽  
В.И. Николаев
Keyword(s):  
Single Crystals ◽  
Experimental Studies ◽  
High Accuracy ◽  
Arithmetic Mean ◽  
Polished Surface ◽  
Average Spacing ◽  
Initial Form ◽  
Profile Deviation ◽  
Subsequent Heating

AbstractWe present the results of experimental studies of the return of Ni–Fe–Ga–Co and Cu–Al–Ni single crystals to the initial form at the macro- and microlevels after their deformation by compression and subsequent restorative heating. It is found that the geometric dimensions of the sample are reproduced with high accuracy (up to 20 μm). The microrelief appearing on the initially polished surface during crystal compression (the arithmetic mean profile deviation R _ a ≈ 0.25–0.75 μm, the average spacing of local protrusions of the profile S ≈ 0.027–0.11 mm) is not removed by subsequent heating and remains with further multiple repetition of deformation–restoration cycles.

Yag Single Crystals for Scintillators of Stem

1990 ◽  
Vol 48 (1) ◽  
pp. 166-167
Author(s):  
M. Hibino ◽  
K. Irie ◽  
R. Autrata ◽  
P. schauer
Keyword(s):  
Single Crystals ◽  
Yttrium Aluminum Garnet ◽  
Light Guide ◽  
Detection System ◽  
Polished Surface ◽  
Detective Quantum Efficiency ◽  
Backscattered Electrons ◽  
Electron Detection ◽  
Yttrium Aluminum ◽  
Phosphor Screens

Although powdered phosphor screens are usually used for scintillators of STEM, it has been found that the phosphor screen of appropriate thickness should be used depending on the accelerating voltage, in order to keep high detective quantum efficiency. 1 It has been also found that the variation in sensitivity, due to granularity of phosphor screens, makes the measurement of fine electron probe difficult and that the sensitivity reduces with electron irradiation specially at high voltages.In order to find out a preferable scintillator for STEM, single crystals of YAG (yttrium aluminum garnet), which are used for detecting secondary and backscattered electrons in SEM were investigated and compared with powdered phosphor screens, at the accelerating voltages of 100kV and 1 MV. A conventional electron detection system, consisting of scintillator, light guide and PMT (Hamamatsu Photonics R268) was used for measurements. Scintillators used are YAG single crystals of 1.0 to 3.2mm thicknesses (with surfaces matted for good interface to the light guide) and of 0.8mm thickness (with polished surface), and powdered P-46 phosphor screens of 0.07mm and 1.0mm thicknesses for 100kV and 1MV, respectively. Surfaces on electron-incidence side of all scintillators are coated with reflecting layers.

The Revised Universal Slope Method to Predict the Low-Cycle Fatigue Lives of Elbow and Tee Pipes

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Hiun Nagamori ◽  
Koji Takahashi
Keyword(s):  
Experimental Data ◽  
Internal Pressure ◽  
Low Cycle Fatigue ◽  
Experimental Studies ◽  
High Accuracy ◽  
Universal Method ◽  
Cycle Fatigue ◽  
Element Analysis ◽  
Slope Method ◽  
Stress States

The stress states of elbow and tee pipes are complex and different from those of straight pipes. The low-cycle fatigue lives of elbows and tees cannot be predicted by Manson's universal slope method; however, a revised universal method proposed by Takahashi et al. was able to predict with high accuracy the low-cycle fatigue lives of elbows under combined cyclic bending and internal pressure. The objective of this study was to confirm the validity of the revised universal slope method for the prediction of low-cycle fatigue behaviors of elbows and tees of various shapes and dimensions under conditions of in-plane bending and internal pressure. Finite element analysis (FEA) was carried out to simulate the low-cycle fatigue behaviors observed in previous experimental studies of elbows and tees. The low-cycle fatigue behaviors, such as the area of crack initiation, the direction of crack growth, and the fatigue lives, obtained by the analysis were compared with previously obtained experimental data. Based on this comparison, the revised universal slope method was found to accurately predict the low-cycle fatigue behaviors of elbows and tees under internal pressure conditions regardless of differences in shape and dimensions.

Research of stamping of unequal channel bars. Part 5. Methods for calculating the extrusion of channels. 2. Extrusion of non-strengthening material

2021 ◽  
pp. 46-52
Author(s):  
A.L. Vorontsov
Keyword(s):  
Plane Strain ◽  
Theoretical Calculations ◽  
Experimental Studies ◽  
High Accuracy ◽  
Experimental Results ◽  
Die Forging

The results of experimental studies on the extrusion of channels from non-strengthening material are presented. Comparison of theoretical calculations with experimental results showed the high accuracy of the derived formulas. Keywords: die forging, extrusion, punch, matrix, misalignment, plane strain. [email protected]

Photoluminescence enhancement and high accuracy patterning of lead halide perovskite single crystals by MeV ion beam irradiation

2020 ◽  
Vol 8 (29) ◽  
pp. 9923-9930 ◽  
Author(s):  
Milan Palei ◽  
M. Motapothula ◽  
Aniruddha Ray ◽  
Ahmed L. Abdelhady ◽  
Luca Lanzano ◽  
...  
Keyword(s):  
Single Crystals ◽  
Ion Irradiation ◽  
Ion Beam ◽  
High Accuracy ◽  
Enhancement Effect ◽  
Beam Irradiation ◽  
Ion Beam Irradiation ◽  
Photoluminescence Enhancement ◽  
Halide Perovskite ◽  
Lead Halide

Using MeV ion irradiation, a PL enhancement effect of MAPbBr3 single crystals is demonstrated.

scholarly journals Wetting and spreading of droplets on rough aluminum surfaces

2019 ◽  
Vol 196 ◽  
pp. 00024
Author(s):  
Anastasia Islamova ◽  
Konstantin Ponomarev
Keyword(s):  
Contact Angle ◽  
Aluminum Alloy ◽  
Dynamic Contact Angle ◽  
Dynamic Contact ◽  
Arithmetic Mean ◽  
Distilled Water ◽  
Roughness Parameters ◽  
Shadow Method ◽  
Profile Deviation ◽  
Aluminum Surfaces

The wetting and spreading of distilled water droplets on abrasion-treated aluminum alloy AlMg 6 surfaces were studied. Using the shadow method, the dependences of the dynamic contact angle and hysteresis on the arithmetic mean of the profile deviation were obtained. Based on the analysis of the height and hybrid 3D roughness parameters, a relationship between the texture and spreading of the droplet is established.

Influence of the Mineralogical and Mortar Components on the Adherence of Some “Granites”

2013 ◽  
Vol 548 ◽  
pp. 267-274 ◽  
Author(s):  
Lizandra Nogami ◽  
Antenor B. Paraguassú ◽  
José E. Rodrigues ◽  
Rogério P. Ribeiro
Keyword(s):  
Bond Strength ◽  
Single Crystals ◽  
Rough Surface ◽  
Tensile Bond Strength ◽  
Polished Surface ◽  
Optical Orientation ◽  
Adhesion Bond ◽  
Strength Tests ◽  
Mineral Components ◽  
Traction Test

Rock plate setting can be performed with metal inserts or by mortar adhesion. For mortar setting, the adhesion bond strength values, as a rule, should be above 1 MPa. In the present work, tests with eight types of “granite” tiles were performed to compare the adherence of five types of mortars. The rocks chosen were: Red Brasilia (syenogranite), Black Indian (migmatite), Green Labrador (charnockite), Black Sao Gabriel (hypersthene diorite), Rose Jacaranda (nebulitic migmatite syenogranite), Fantastic Blue (biotite monzogranite megaporphyritic serial gneissified), Grey Swallow (monzogranite) and Yellow Ornamental (garnet porphyroblastic gneiss), which do not have similar petrographic and sawability characteristics, thereby resulting in different initial roughness values of the plates obtained by breaking apart the blocks on the gangsaw machine, which use granulated steel as an abrasive element. The adherence of these rocks with the mortars was determined in the rough surface as well as in the polished surface by the pullout traction test, standardized for ceramics. The results showed that the mortar adhesion is related to roughness, to mineralogy and to the texture of these rocks. To verify this relationship, tensile bond strength tests were performed with the main mineral components of these rocks using single crystals with known optical orientation. Moreover, the microstructure study of the standard substrate/mortar/rock set was also performed.

Experimental Studies of Hollow-Core Screw Dislocations in 6H-SiC and 4H-SiC Single Crystals

1998 ◽  
Vol 264-268 ◽  
pp. 429-432 ◽  
Author(s):  
W. Si ◽  
Michael Dudley ◽  
R.C. Glass ◽  
Calvin H. Carter Jr. ◽  
Valeri F. Tsvetkov
Keyword(s):  
Single Crystals ◽  
Experimental Studies ◽  
Hollow Core ◽  
Screw Dislocations

Vertical refraction determination using a Trimble S9 total station

2020 ◽  
Vol 954 (12) ◽  
pp. 2-9
Author(s):  
D.V. Dementiev ◽  
I.M. Zhukov ◽  
M.Y. Karavanov ◽  
I.I. Ranov ◽  
N.Yu. Litvinov
Keyword(s):  
Atmospheric Turbulence ◽  
Turbulent Atmosphere ◽  
Measurement Accuracy ◽  
Dynamic Method ◽  
Experimental Studies ◽  
High Accuracy ◽  
Measuring Instruments ◽  
Total Station ◽  
The Real

Classical methods for determining refraction are based on Newton’s formulae for a statically stable atmosphere. However, they do not provide the required measurement accuracy due to random changes in refraction, caused by the influence of atmospheric turbulence. The aim of this work is to study the dynamic method for determining refraction in a turbulent atmosphere. The measurements were performed with a Trimble S9 total station. It was found out, that within a few seconds the angle of vertical refraction can change by dozens of arc seconds. To improve the accuracy of the results, it is necessary to determine the refraction instantly for a specific moment of observation and for a particular path, otherwise the obtained corrections will not correspond to the real angle of refraction. The introduction of a dynamic method for determining refraction requires more extensive experimental studies under various observation conditions. In the case of confirmation of the high accuracy of the dynamic method for determining the fraction, significant prospects open up for taking refraction into account and developing new more effective measuring instruments in a turbulent atmosphere.

scholarly journals Influence of the Non-Schmid Effects on the Ductility Limit of Polycrystalline Sheet Metals

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1386 ◽  
Author(s):  
Mohamed Ben Bettaieb ◽  
Farid Abed-Meraim
Keyword(s):  
Single Crystal ◽  
Mechanical Behavior ◽  
Single Crystals ◽  
Plastic Flow ◽  
Yield Criterion ◽  
Experimental Studies ◽  
Crystallographic Structure ◽  
Sheet Metals ◽  
Localized Necking ◽  
The Impact

The yield criterion in rate-independent single crystal plasticity is most often defined by the classical Schmid law. However, various experimental studies have shown that the plastic flow of several single crystals (especially with Body Centered Cubic crystallographic structure) often exhibits some non-Schmid effects. The main objective of the current contribution is to study the impact of these non-Schmid effects on the ductility limit of polycrystalline sheet metals. To this end, the Taylor multiscale scheme is used to determine the mechanical behavior of a volume element that is assumed to be representative of the sheet metal. The mechanical behavior of the single crystals is described by a finite strain rate-independent constitutive theory, where some non-Schmid effects are accounted for in the modeling of the plastic flow. The bifurcation theory is coupled with the Taylor multiscale scheme to predict the onset of localized necking in the polycrystalline aggregate. The impact of the considered non-Schmid effects on both the single crystal behavior and the polycrystal behavior is carefully analyzed. It is shown, in particular, that non-Schmid effects tend to precipitate the occurrence of localized necking in polycrystalline aggregates and they slightly influence the orientation of the localization band.

Sign in / Sign up

Export Citation Format

Share Document