scholarly journals Onnanoscale phenomena inthe electroacoustic sputtering process

2019 ◽  
Vol 18 (4) ◽  
pp. 401-407
Author(s):  
W. H. Al-Tibbi ◽  
V. S. Minakov
Keyword(s):  
Amorphous Phase ◽  
Layer Structure ◽  
Nanocrystalline Structure ◽  
Coherent Scattering ◽  
Process Conditions ◽  
Diffraction Reflection ◽  
Scattering Method ◽  
X Ray ◽  
Nanocrystalline Structures ◽  
Machine Parts

Introduction. The effect of variable parameters of the electroacoustic sputtering (ELAS) process on the characteristics of the crystalline structure of hardening coatings is studied. The ELAS parameter values providing nanostructured cover coatings for machine parts and cutting tools are determined. Hardening through using such coatings allows achieving a significant (5-10 times) increase in the life of hardenable machine parts and various tools designed for mechanical processing. To obtain coatings with the desired properties of the surface layer, nanocrystalline materials should be selected. In this case, a certain content of the amorphous phase is permissible.Materials and Methods. To carry out the X-ray structural analysis, the X-ray diffraction Russian-made device DRON-3M was used. The Scherrer-Wilson method was applied to determine the granularity of particle blocks from the value of the intrinsic broadening of the diffractogram peaks. The conclusions obtained in this paper are based on the method of separation of the affecting factor contributions into broadening the diffraction reflection peaks (the Warren-Averbach method).Research Results. Depending on the process conditions and the technique for obtaining nanostructured materials, a nonuniquely interpretable change in the indices of the diffraction peaks broadening occurs, which is generally characteristic of nanocrystalline metals. One of the possible explanations for this phenomenon is the presence of a nanosized effect in the hardened layer. The occurrence of the nanocrystalline structure in the sputtered layer verifies the calculated values of the dimensions of the coherent scattering regions (CSR). The occurrence of affecting values of the misorientation angle of the crystal structure is verified by the CSR value for the investigated 110 and 220 reflexes, which is supported by a high percentage of the amorphous phase.Discussion and Conclusions. The electroacoustic scattering method is promising for obtaining nanocrystalline structures in the surface and subsurface layers of the sprayed samples. The ELAS process variables variation leads to the parameter spread of the crystal lattice and coherent scattering areas. In this case, there is no definite trend. In the future it is expected to solve the given problem. First, experiments will be conducted to determine the optimal sputtering regimes that could stimulate the formation of nanocrystalline structures. Secondly, visual observation and evaluation of the sprayed layer structure using electron microscopy is planned.

Amorphization mechanisms of NiZr2 by ball-milling

1997 ◽  
Vol 12 (3) ◽  
pp. 688-696 ◽  
Author(s):  
D. Galy ◽  
L. Chaffron ◽  
G. Martin
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ball Milling ◽  
Amorphous Phase ◽  
Shear Waves ◽  
Nanocrystalline Structure ◽  
Nanocrystalline Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron

The microstructure of NiZr2 in the course of amorphization by ball-milling is studied by transmission electron microscopy (TEM) and x-ray diffraction (XRD). The evolution from the initial fully crystalline alloy to a fully amorphized material is described. It is shown that prior to amorphization, the powder aggregates achieve a 100% nanocrystalline structure; the amorphous phase then appears and develops to the expense of the nanocrystalline phase. No massive chemical disordering is observed, but a small amount cannot be ruled out. It is proposed that amorphization occurs by chemical disordering at interfaces, induced by the scattering of shear waves.

scholarly journals Induced Spirals in Polyethylene Terephthalate Films Irradiated with Ar Ions with an Energy of 70 MeV

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 427 ◽  
Author(s):  
Adil Z. Tuleushev ◽  
Maxim V. Zdorovets ◽  
Artem L. Kozlovskiy ◽  
Fiona Erica Harrison
Keyword(s):  
Polyethylene Terephthalate ◽  
Electric Fields ◽  
Temporal Stability ◽  
Coherent Scattering ◽  
Amorphous Region ◽  
Diffraction Reflection ◽  
X Ray ◽  
Spiral Structures ◽  
Amorphous Zone ◽  
Pet Film

This paper presents the results of a study of the ordering in polyethylene terephthalate (PET) film induced by Ar8+ ions with an irradiation fluence of 2 × 1012 ions/cm2, and of the temporal stability of the induced ordering in the irradiated sample, over a three month period. Immediately after irradiation, sharp new reflections not seen at lower fluences were observed in X-ray diffraction patterns, with angular positions of 2 θ = 9–10° and 19° and variable azimuthal intensities. X-ray reflections, previously observed at lower fluences, were also seen: at 2 θ = 26° and 23°, associated with PET crystallites, and at 2 θ = 5–12°, associated with induced ordering in the amorphous zone. Aging of the irradiated sample led to significant growth of the ordering region in the amorphous zone for angles up to 2 θ < 15°, as well as to dissipation and blurring of the new diffraction reflections at 2 θ = 9–10° and 2 θ = 19° and the formation of a new diffraction ring reflection in the range 2 θ = 11–16°. The azimuthal distribution of diffraction reflection intensities immediately after irradiation displays a clear oblique cross located predominantly along lines at angles of π/4 with respect to the direction of the texture of the PET film, indicating the formation of spiral structures based on the molecular strands of PET. Our experimental results lead us to conclude that the formation of coherent scattering areas in the amorphous region at 2 θ < 15° is due to intra-chain rotations of benzene-carboxyl subunits of repeat units of the PET chain molecules interacting with the residual electric field of a single latent track; whereas the formation of spiral structures is due to the inter-chain interaction of these preordered asymmetric subunits under the influence of the electric fields from overlapping latent tracks.

scholarly journals Quantitative analysis of diffuse X-ray scattering in partially transformed 3C-SiC single crystals

2010 ◽  
Vol 43 (4) ◽  
pp. 867-875 ◽  
Author(s):  
A. Boulle ◽  
D. Dompoint ◽  
I. Galben-Sandulache ◽  
D. Chaussende
Keyword(s):  
Single Crystals ◽  
Diffuse Scattering ◽  
Layer Structure ◽  
Coherent Scattering ◽  
Theoretical Description ◽  
X Ray ◽  
Partial Dislocations ◽  
X Ray Scattering ◽  
Wide Range ◽  
Ray Scattering

The X-ray scattering of partially transformed 3C-SiC single crystals is considered in detail. Extended diffuse scattering streaks, originating from stacking faults (SFs) lying in the {111} planes, are clearly observed in the wide-range reciprocal-space maps. The intensity distribution along the diffuse streaks is simulated with a model including the contributions of the diffuse scattering originating from the SFs [based on the pioneering theoretical description given by Kabra, Pandey & Lele (1986).J. Mater. Sci.21, 1654–1666], the coherent scattering emanating from untransformed areas of the crystals and all θ-dependent terms that affect the scattered intensity (the layer structure factor, the irradiated volume and the polarization of the beam). The quantitative simulation of the diffuse streaks reveals that the transformation occurs through the glide of partial dislocations and allows one to derive the transformation level. It is shown that the 3C polytype is indeed unstable at high temperature. However, it is further shown that defect-free 3C-SiC single crystals remain stable at temperatures where 3C-SiC is known to be usually unstable (2173 K). The origin of this apparent stability is very likely of kinetic nature,i.e.the lack of crystalline defects inhibits the transformation.

WC-Co Detonation Coatings Having a Hybrid Amorphous-Nanocrystalline Structure Display Improved Properties

1997 ◽  
Author(s):  
T. Shmyreva ◽  
V. Britun
Keyword(s):  
Metallic Matrix ◽  
Nanocrystalline Structure ◽  
Hybrid Structures ◽  
Flame Spraying ◽  
Void Content ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Nanocrystalline Structures ◽  
Detonating Gas

Abstract X ray diffraction and transmission electron microscopy studies and measurements of hardness and void content were carried out for WC-20% Co coatings produced by detonation flame spraying at various oxygen/acetylene ratios in the detonating gas mixture. It was demonstrated that successive transition from (WC+Co) to (W2C+Co3W3C) to (W+CO7W6) occurs as the oxygen content in the mixture is increased, and that amorphous-nanocrystalline structures form in the coating. Two types of these hybrid structures were revealed, one including an amorphous metallic matrix containing precipitates of intermetallic nanocrystals, the other having an amorphous oxide matrix and nanocrystalline precipitates of CO3O4 and WO3. The hybrid structures were shown to improve coating density and hardness.

Studies of Severe Plastic Deformation Conditions for Amorphous and Nanocrystalline Structures Formation in Ti-Ni Based Alloys

2006 ◽  
Vol 503-504 ◽  
pp. 481-486 ◽  
Author(s):  
Sergey Prokoshkin ◽  
I. Khmelevskaya ◽  
Sergey V. Dobatkin ◽  
E.V. Tatyanin ◽  
I.B. Trubitsyna
Keyword(s):  
Deformation Temperature ◽  
High Pressure Torsion ◽  
Nanocrystalline Structure ◽  
Amorphous Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Angular Pressing ◽  
Ni Alloy ◽  
Nanocrystalline Structures ◽  
Isothermal Martensitic Transformation

Structure formation in TiNi-based shape memory alloys depending on deformation temperature (-196 °C to 400 °C) and pressure (4 to 8 GPa) under conditions of high-pressure torsion (HPT) was studied using TEM and X-ray diffraction methods. The tendency to form an amorphous structure depends on relative positions of the deformation temperature and Ms temperature. Isothermal martensitic transformation is observed in the Ti – 48.5 % Ni alloy as a result of 10-year keeping at RT after HPT. Increasing of pressure suppresses the tendency to form an amorphous structure. The upper deformation temperature limits for amorphous and nanocrystalline structures formation are determined. The thermomechanical conditions of the equal-channel angular pressing for obtaining actual nanocrystalline structure are recommended.

scholarly journals Characterization of a back-illuminated CMOS camera for soft x-ray coherent scattering

2019 ◽  
Author(s):  
Kewin Desjardins ◽  
Horia Popescu ◽  
Pascal Mercère ◽  
Claude Menneglier ◽  
Roland Gaudemer ◽  
...  
Keyword(s):  
Coherent Scattering ◽  
Cmos Camera ◽  
X Ray ◽  
Back Illuminated

The Application of X-Ray Diffraction at Elevated Temperatures to Study the Mechanism of Formation of Sodium Tripolyphosphate

1961 ◽  
Vol 5 ◽  
pp. 276-284
Author(s):  
E. L. Moore ◽  
J. S. Metcalf
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Amorphous Phase ◽  
Elevated Temperatures ◽  
Sodium Tripolyphosphate ◽  
X Ray Diffraction ◽  
Mechanism Of Formation ◽  
X Ray ◽  
Temperature Form ◽  
High Temperature Form

AbstractHigh-temperature X-ray diffraction techniques were employed to study the condensation reactions which occur when sodium orthophosphates are heated to 380°C. Crystalline Na4P2O7 and an amorphous phase were formed first from an equimolar mixture of Na2HPO4·NaH2PO4 and Na2HPO4 at temperatures above 150°C. Further heating resulted in the formation of Na5P3O10-I (high-temperature form) at the expense of the crystalline Na4P4O7 and amorphous phase. Crystalline Na5P3O10-II (low-temperature form) appears after Na5P3O10-I.Conditions which affect the yield of crystalline Na4P2O7 and amorphous phase as intermediates and their effect on the yield of Na5P3O10 are also presented.

scholarly journals Estimation of Wear Resistance for Multilayer Coatings Obtained by Nitrogenchroming

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1153
Author(s):  
Ivan Pavlenko ◽  
Jozef Zajac ◽  
Nadiia Kharchenko ◽  
Ján Duplák ◽  
Vitalii Ivanov ◽  
...  
Keyword(s):  
Wear Resistance ◽  
Spectral Analysis ◽  
Friction Coefficient ◽  
Cutting Tools ◽  
Wear Intensity ◽  
Maximum Amount ◽  
Multilayer Coatings ◽  
Wear Depth ◽  
X Ray ◽  
Machine Parts

This article deals with improving the wear resistance of multilayer coatings as a fundamental problem in metal surface treatment, strengthening elements of cutting tools, and ensuring the reliability of machine parts. It aims to evaluate the wear depth for multilayer coatings by the mass loss distribution in layers. The article’s primary purpose is to develop a mathematical method for assessing the value of wear for multilayer steel-based coatings. The study material is a multilayer coating applied to steel DIN C80W1. The research was performed using up-to-date laboratory equipment. Nitrogenchroming has been realized under overpressure in two successive stages: nitriding for 36 h at temperature 540 °C and chromizing during 4 h at temperature 1050 °C. The complex analysis included several options: X-ray phase analysis, local micro-X-ray spectral analysis, durometric analysis, and determination of wear resistance. These analyses showed that after nitrogenchroming, the three-layer protective coating from Cr23C6, Cr7C3, and Cr2N was formed on the steel surface. Spectral analysis indicated that the maximum amount of chromium 92.2% is in the first layer from Cr23C6. The maximum amount of carbon 8.9% characterizes the layer from Cr7C3. Nitrogen is concentrated mainly in the Cr2N layer, and its maximum amount is 9.4%. Additionally, it was determined that the minimum wear is typical for steel DIN C80W1 after nitrogenchroming. The weight loss of steel samples by 25 mg was obtained. This value differs by 3.6% from the results evaluated analytically using the developed mathematical model of wear of multilayer coatings after complex metallization of steel DIN C80W1. As a result, the impact of the loading mode on the wear intensity of steel was established. As the loading time increases, the friction coefficient of the coated samples decreases. Among the studied samples, plates from steel DIN C80W1 have the lowest friction coefficient after nitrogenchroming. Additionally, a linear dependence of the mass losses on the wearing time was obtained for carbide and nitride coatings. Finally, an increase in loading time leads to an increase in the wear intensity of steels after nitrogenchroming. The achieved scientific results are applicable in developing methods of chemical-thermal treatment, improving the wear resistance of multilayer coatings, and strengthening highly loaded machine parts and cutting tools.

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