scholarly journals Structure and properties of layer, surfaced on HARDOX 450 steel by boron containing wire

2019 ◽  
Vol 62 (8) ◽  
pp. 613-620
Author(s):  
Yu. F. Ivanov ◽  
V. E. Gromov ◽  
D. A. Romanov ◽  
A. A. Klopotov ◽  
Yu. A. Rubannikova
Keyword(s):  
Crystal Lattice ◽  
Cross Sections ◽  
Iron Boride ◽  
Initial State ◽  
Scalar Density ◽  
State Diagrams ◽  
Α Phase ◽  
Transmission Electron ◽  
High Microhardness ◽  
High Level

Analysis of structure phase states and properties of the layers formed on HARDOX 450 low alloy steel by welded-on wires with boron content of 4.5 and 6.5 % wt. was made by the methods of modern physical material science. In the initial state HARDOX 450 steel has the structure of tempered martensite, in the volume and along the boundaries of crystals of it the cementite particles are located. The particles located in the volume have acicular shape and those along boundaries are mainly round. The presence of extinction bend contours has been revealed, indicative of the curvature torsion of crystal lattice of the material’s portion. They originate and finish on the interfaces of martensite crystals. Scalar density of chaotically located dislocations and forming the netlike substructure is 6.2·1010 cm–2. The layer welded on HARDOX 450 steel has microhardness increasing by more than two-fold that of the base. Analysis of state diagrams of Fe – C, Fe – B, B – C systems and polythermal cross–sections in Fe – C – B system has shown that the rapid cooling of Fe23C6 – Fe23B6 alloys from liquid state would facilitate the formation of multiphase structural states. It is stated by the methods of transmission electron diffraction microscopy that the reasons for the high microhardness level of the surface layers are the following: formation of iron borides and crystals of ultafine-dispersion (up to 100 nm) packet martensite with high level (~1011 cm–2 ) of scalar density of dislocations; presence of nanodimentional particles of iron and boron carbides in the volume and on the boundaries of martensite crystals; high level of curvature torsion of crystal lattice of iron borides and α-phase grains, caused by the internal stress fields along interphase (interface of iron boride crystals and α-phase grains) and intraphase boundaries (interface of iron borides and martensite crystals packet). Increase in boron concentration from 4.5 to 6.5 % is accompanied by the sufficient increase (by 1.2 – 1.5 times) in hardness of welded layer. It is caused by the increase of dimensions and relative content of iron boride regions by 1.5 – 2.0 times.

scholarly journals Change of 0.34Cr-1Ni-Mo-Fe Steel Dislocation Structure in Plasma Electrolyte Hardening

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1928
Author(s):  
Bauyrzhan Rakhadilov ◽  
Zarina Satbayeva ◽  
Sherzod Ramankulov ◽  
Nurdaulet Shektibayev ◽  
Laila Zhurerova ◽  
...  
Keyword(s):  
Crystal Lattice ◽  
Dislocation Structure ◽  
Volume Fraction ◽  
Internal Stresses ◽  
Shear Stresses ◽  
Initial State ◽  
Α Phase ◽  
Quantitative Characteristics ◽  
Before And After ◽  
Plasma Electrolytic

This work deals with the study of changes in the dislocation structure and quantitative characteristics, as well as morphological components, of 0.34Cr-1Ni-Mo-Fe steel before and after plasma electrolytic hardening. According to the electron microscopic studies of the fine structure of 0.34Cr-1Ni-Mo-Fe steel before and after plasma electrolytic hardening, 0.34Cr-1Ni-Mo-Fe steel is a multiphase material containing an α-phase, a γ-phase (retained austenite), and a cementite and carbide phase. It was revealed that, morphologically, the α-phase in the initial state, generally, is present in the form of: lamellar pearlite with a volume fraction of 35%, a ferritocarbide mixture with a volume fraction of 45%, and fragmented ferrite with a volume fraction of 20% of the material. After surface hardening, the morphological components of the structure changed: packet–lamellar martensite with volume fractions of 60% and 40%, 5% and 7% of γ-phase as residual austenite in the crystals of packet–lamellar martensite, 0.6% and 1.5% of cementite in crystals of packet–lamellar martensite, and 0.15% and 0.35% of complex carbide М23С6 in crystals of packet–lamellar martensite, respectively, were observed. The quantitative characteristics of the dislocation structure were estimated by the following calculated indices of packet and lamellar martensite: scalar (ρ) and excess (ρ±) density of dislocations, the value of the curvature-torsion of the crystal lattice (χ), the amplitude of long-range internal stresses (σd), and the amplitude of shear stresses (σL), according to which the plastic nature of the bending-torsion of the crystal lattice was confirmed (σL > σd).

scholarly journals Кристаллографические особенности структуры литых и закаленных сплавов кобальт--ниобий

2020 ◽  
Vol 90 (7) ◽  
pp. 1103
Author(s):  
Ю.В. Хлебникова ◽  
Л.Ю. Егорова ◽  
Т.Р. Суаридзе ◽  
Ю.Н. Акшенцев
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Polymorphic Transformation ◽  
Room Temperature ◽  
Fine Grained ◽  
Α Phase ◽  
Transmission Electron ◽  
Cast Alloys ◽  
High Level ◽  
Subsequent Quenching

By the means of metallography, scanning and transmission electron microscopy, and EBSD-analysis, the features of the structure formation upon β→α (fcc-hcp) - polymorphic transformation in Co - Nb binary alloys were studied. It was shown that upon gradual cooling of the crystallized ingot, in each β-grain of the alloy nucleation of the α-phase crystals of several orientations out of 4 possible in accordance with the Wasserman’s orientational relations occurs. The formation of any of the 4 possible orientations of the α-phase is equally probable. At room temperature, only α (hcp)-martensite was found in the structure of the studied alloys. The misorientation of the substructure in the martensitic crystals length-wise in cast alloys does not exceed 1 deg. After the homogenization and the subsequent quenching in salted water, the structure of Co-Nb alloys does not undergo neither morphological, nor crystallographic changes, but becomes noticeably more fine-grained. In this case, the misorientation of the substructure elements of the martensitic crystals length-wise increases several times, consequent to the high level of quenching microstresses in martensite. No phases with multilayer lattices such as NR martensite were found.

Measurement of Crystal Lattice Rotations under Nanoindents in Copper

2004 ◽  
Vol 841 ◽  
Author(s):  
Kirsten K. McLaughlin ◽  
Nadia A. Stelmashenko ◽  
Stephen J. Lloyd ◽  
Luc J. Vandeperre ◽  
William J. Clegg
Keyword(s):  
Electron Microscopy ◽  
Crystal Lattice ◽  
Cross Sections ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Convergent Beam Electron Diffraction ◽  
Copper Crystal ◽  
Beam Electron ◽  
Transmission Electron ◽  
Convergent Beam

ABSTRACTA technique is described to measure the rotations of the crystal lattice in the deformed region around a nanoindent from volumes smaller than 3 × 10−5 μm3. To demonstrate this method, a copper crystal has been indented on its (001) face to depths of 500 and 1300 nm. Cross-sections of nanoindents were prepared for transmission electron microscopy by focused ion beam milling, and rotations were measured about the [001], [010] and [100] axes using convergent beam electron diffraction.

Direct Observation of Heat Exchanger Deposits by Cross Sectioning

1967 ◽  
Vol 25 ◽  
pp. 364-365
Author(s):  
R. W. Anderson ◽  
D. L. Senecal
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Heat Exchanger ◽  
Direct Observation ◽  
Cross Sections ◽  
Preparation Method ◽  
Specimen Preparation ◽  
Flowing Water ◽  
Transmission Electron ◽  
Deposit Layer

A problem was presented to observe the packing densities of deposits of sub-micron corrosion product particles. The deposits were 5-100 mils thick and had formed on the inside surfaces of 3/8 inch diameter Zircaloy-2 heat exchanger tubes. The particles were iron oxides deposited from flowing water and consequently were only weakly bonded. Particular care was required during handling to preserve the original formations of the deposits. The specimen preparation method described below allowed direct observation of cross sections of the deposit layers by transmission electron microscopy.The specimens were short sections of the tubes (about 3 inches long) that were carefully cut from the systems. The insides of the tube sections were first coated with a thin layer of a fluid epoxy resin by dipping. This coating served to impregnate the deposit layer as well as to protect the layer if subsequent handling were required.

Comparison of ultra high resolution immersion lens CFESEM and TEM for imaging of semiconductor devices

1990 ◽  
Vol 48 (4) ◽  
pp. 622-623
Author(s):  
Terrence Reilly ◽  
Al Pelillo ◽  
Barbara Miner
Keyword(s):  
High Resolution ◽  
Sample Preparation ◽  
Cross Sections ◽  
Semiconductor Devices ◽  
Ion Milling ◽  
Observation Area ◽  
Transmission Electron ◽  
Milling Machines ◽  
Resolution Imaging ◽  
Electron Microscopes

The use of transmission electron microscopes (TEM) has proven to be very valuable in the observation of semiconductor devices. The need for high resolution imaging becomes more important as the devices become smaller and more complex. However, the sample preparation for TEM observation of semiconductor devices have generally proven to be complex and time consuming. The use of ion milling machines usually require a certain degree of expertise and allow a very limited viewing area. Recently, the use of an ultra high resolution "immersion lens" cold cathode field emission scanning electron microscope (CFESEM) has proven to be very useful in the observation of semiconductor devices. Particularly at low accelerating voltages where compositional contrast is increased. The Hitachi S-900 has provided comparable resolution to a 300kV TEM on semiconductor cross sections. Using the CFESEM to supplement work currently being done with high voltage TEMs provides many advantages: sample preparation time is greatly reduced and the observation area has also been increased to 7mm. The larger viewing area provides the operator a much greater area to search for a particular feature of interest. More samples can be imaged on the CFESEM, leaving the TEM for analyses requiring diffraction work and/or detecting the nature of the crystallinity.

scholarly journals Oxygen Induced Phase Transformation in TC21 Alloy with a Lamellar Microstructure

Metals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 163
Author(s):  
Shu Wang ◽  
Yilong Liang ◽  
Hao Sun ◽  
Xin Feng ◽  
Chaowen Huang
Keyword(s):  
Electron Microscopy ◽  
Phase Transformation ◽  
Oxygen Uptake ◽  
Titanium Alloys ◽  
Electron Backscatter Diffraction ◽  
Lamellar Microstructure ◽  
Α Phase ◽  
Transmission Electron ◽  
The Matrix ◽  
Oxygen Ingress

The main objective of the present study was to understand the oxygen ingress in titanium alloys at high temperatures. Investigations reveal that the oxygen diffusion layer (ODL) caused by oxygen ingress significantly affects the mechanical properties of titanium alloys. In the present study, the high-temperature oxygen ingress behavior of TC21 alloy with a lamellar microstructure was investigated. Microstructural characterizations were analyzed through optical microscopy (OM), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM). Obtained results demonstrate that oxygen-induced phase transformation not only enhances the precipitation of secondary α-phase (αs) and forms more primary α phase (αp), but also promotes the recrystallization of the ODL. It was found that as the temperature of oxygen uptake increases, the thickness of the ODL initially increases and then decreases. The maximum depth of the ODL was obtained for the oxygen uptake temperature of 960 °C. In addition, a gradient microstructure (αp + β + βtrans)/(αp + βtrans)/(αp + β) was observed in the experiment. Meanwhile, it was also found that the hardness and dislocation density in the ODL is higher than that that of the matrix.

Preparation of α-Ni(OH)2 with Flowerlike Hierarchical Architectures via Homogeneous Precipitation Method

2011 ◽  
Vol 284-286 ◽  
pp. 684-687
Author(s):  
Chang Yu Li ◽  
Li Li Liu ◽  
Shou Xin Liu
Keyword(s):  
Electron Microscopy ◽  
Precipitation Method ◽  
Homogeneous Precipitation ◽  
X Ray ◽  
Homogeneous Precipitation Method ◽  
Α Phase ◽  
Transmission Electron ◽  
Hierarchical Architectures ◽  
Flowerlike Structure ◽  
Adsorption Desorption

Without using any templates or surfactants, flowerlike α-nickel hydroxide (Ni(OH)2) was successfully synthesized by homogeneous precipitation method. The prepared products were characterized by X-ray powder diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and N2 adsorption-desorption. The prepared Ni(OH)2 is α-phase with specific surface area of 245.0 m2/g and shows flowerlike structure with 4-6 um in diameter.

Investigation on the Origin of Magnetization in Plastically Deformed NI51TI49 Alloy

2017 ◽  
Vol 743 ◽  
pp. 13-18
Author(s):  
Anna Drozdova ◽  
Alexander Nyavro ◽  
Lyudmila Kveglis
Keyword(s):  
Crystal Lattice ◽  
Magnetic Moments ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Lattice Curvature ◽  
Electron States ◽  
Large Atom ◽  
Transmission Electron ◽  
Large Distortion ◽  
Density Of Electron States

The article deals with the investigation of structure and magnetic properties of plastically deformed Ni51Ti49 alloy. The magnetic hysteresis loops confirm the presence of ferromagnetic properties in the alloy. The transmission electron microscopy (TEM) detects the appearance of lenticular crystals with bending contours which indicate the large distortion of the crystal lattice. The crystal lattice curvature occurs due to the large atom displacement. As a result, icosahedral clusters with the Frank-Kasper (FK) structure can be formed. The spin-polarized density of electron states and the magnetic moments for both non-deformed (near-spherical structure) and deformed (elongated by 5% along the Z-axis) Ni7Ti5 (FK-12), Ni8Ti5 (FK-13), and Ni10Ti6 (FK-16) clusters are calculated for the explanation of possibility of magnetization appearance in Ni51Ti49 alloy. The calculations show the increase in the magnetic moments for the deformed clusters. The calculated spectra demonstrate the high density of electron states near the Fermi level which is a characteristic feature of ferromagnetic alloys.

Role of interfacial interactions to control the extent of wrapping of polymer chains on multi-walled carbon nanotubes

RSC Advances ◽  
2016 ◽  
Vol 6 (48) ◽  
pp. 42334-42346 ◽  
Author(s):  
Suchitra Parija ◽  
Arup R. Bhattacharyya
Keyword(s):  
Polymer Chains ◽  
Electron Microscopic ◽  
Α Phase ◽  
Transmission Electron ◽  
Transmission Electron Microscopic ◽  
Electron Microscopic Image ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes ◽  
Transmission Electron Microscopic Image

Transmission electron microscopic image of separated MWCNTs (N51L15G5) showing the wrapped polymer chains on the MWCNTs surface, which corresponds to the α-phase of the PP.

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