scholarly journals Grain Growth Mechanism of Lamellar-Structure High-Purity Nickel via Cold Rolling and Cryorolling during Annealing

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4025
Author(s):  
Zhide Li ◽  
Yuze Wu ◽  
Zhibao Xie ◽  
Charlie Kong ◽  
Hailiang Yu
Keyword(s):  
Grain Growth ◽  
Growth Mechanism ◽  
High Purity ◽  
Lamellar Structure ◽  
Room Temperature ◽  
Rolling Process ◽  
Deformation Energy ◽  
Different Temperatures ◽  
Continuous Recrystallization ◽  
Room Temperature Rolling

High-purity (99.999%) nickel with lamellar-structure grains (LG) was obtained by room-temperature rolling and cryorolling in this research, and then annealed at different temperatures (75 °C, 160 °C, and 245 °C). The microstructure was characterized by transmission electron microscopy. The grain growth mechanism during annealing of the LG materials obtained via different processes was studied. Results showed that the LG high-purity nickel obtained by room-temperature rolling had a static discontinuous recrystallization during annealing, whereas that obtained by cryorolling underwent static and continuous recrystallization during annealing, which was caused by the seriously inhibited dislocation recovery in the rolling process under cryogenic conditions, leading to more accumulated deformation energy storage in sheets.

scholarly journals Evolution of Power Losses in Bending Rolled Fully Finished NO Electrical Steel Treated under Unconventional Annealing Conditions

Materials ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2200 ◽  
Author(s):  
Ivan Petryshynets ◽  
František Kováč ◽  
Ján Füzer ◽  
Ladislav Falat ◽  
Viktor Puchý ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Grain Growth ◽  
Electrical Steel ◽  
Magnetic Measurements ◽  
Boundary Migration ◽  
Stress Relief ◽  
Rolling Process ◽  
Deformation Energy ◽  
Conventional Heat Treatment ◽  
Dynamic Heating

Currently, the non-oriented (NO) iron-silicon steels are extensively used as the core materials in various electrical devises due to excellent combination of their mechanical and soft magnetic properties. The present study introduces a fairly innovative technological approach applicable for fully finished NO electrical steel before punching the laminations. It is based on specific mechanical processing by bending and rolling in combination with subsequent annealing under dynamic heating conditions. It has been revealed that the proposed unconventional treatment clearly led to effective improvement of the steel magnetic properties thanks to its beneficial effects involving additional grain growth with appropriate crystallographic orientation and residual stress relief. The philosophy of the proposed processing was based on employing the phenomena of selective grain growth by strain-induced grain boundary migration and a steep temperature gradient through the cross-section of heat treated specimens at dynamic heating conditions. The stored deformation energy necessary for the grain growth was provided by plastic deformation induced within the studied specimens during the bending and rolling process. The magnetic measurements clearly show that the specimens treated according to our approach exhibited more than 17% decrease in watt losses in comparison with the specimens treated by conventional heat treatment leading only to stress relief without additional grain growth.

Analysis of Tube-Tubesheet Joint Loading Including Thermal Loading

1984 ◽  
Vol 51 (2) ◽  
pp. 339-344 ◽  
Author(s):  
A. I. Soler ◽  
Xu Hong
Keyword(s):  
Thermal Cycling ◽  
Finite Deformation ◽  
Room Temperature ◽  
Thermal Loading ◽  
Computer Code ◽  
Rolling Process ◽  
Two Dimensional ◽  
Incremental Analysis ◽  
Plastic Analysis ◽  
Room Temperature Rolling

The tube-to-tubesheet rolling process is reexamined using a two-dimensional elastic plastic analysis. In addition to room temperature rolling, subsequent thermal cycling of the joint is considered. The development of a computer code based on an incremental analysis that includes finite deformation effects and the possibility of reversed yield is presented. Typical simulations are presented that indicate some of the influences of geometry, materials, and loading on final tube-to-tubesheet contact pressure.

Microstructure Evolution in Bulk Nanostructured Copper during Repeated Cold Rolling

2012 ◽  
Vol 248 ◽  
pp. 43-47
Author(s):  
Lei Liu ◽  
Han Zhuo Zhang ◽  
Qin Lan Zhao
Keyword(s):  
Grain Size ◽  
Cold Rolling ◽  
Grain Growth ◽  
Microstructure Evolution ◽  
Room Temperature ◽  
Maximum Value ◽  
Deformation Stages ◽  
Average Grain Size ◽  
Dislocation Interactions ◽  
Room Temperature Rolling

Room temperature rolling tests were performed on a bulk nanostructured Cu with an average grain size of 90 nm. The results indicated a high thickness reduction ( ) of 92% without crack and an increased {220} texture as the rolling processes continued. Microstructure evolution of the deformed nanostructured Cu could be characterized by several deformation stages. Grain growth and coalescence was prevalent in the early deformation stage, while grain boundaries were impaired and replaced by dislocation interactions when 24%. Microhardness of the deformed nanostructured Cu increased sharply to a maximum value of 1.61 GPa at 8% and then slightly decreased to 1.58 GPa at 92%.

Continuous Recrystallization Phenomenon in High Purity Copper during Equal Channel Angular Pressing up to High Strain at Room Temperature

2008 ◽  
Vol 584-586 ◽  
pp. 929-937 ◽  
Author(s):  
Jing Tao Wang ◽  
Yue Zhang ◽  
Jin Qiang Liu
Keyword(s):  
Grain Boundaries ◽  
Equal Channel Angular Pressing ◽  
High Purity ◽  
Room Temperature ◽  
High Strain ◽  
Large Angle ◽  
Tensile Yield Strength ◽  
Angular Pressing ◽  
Continuous Recrystallization ◽  
Purity Copper

Equal channel angular pressing (ECAP) was conducted at room temperature to a high strain level of ~24 in high purity copper. Tensile testing, Transition Electron Microscopy (TEM) and Electron backscatter diffraction (EBSD) were used to characterize the microstructure and property evolution with the increase of ECAP strain. It was found that tensile yield strength and the stored energy increases upon ECAP processing until a peak reached at 8~12 passes of ECAP, and their saturation was observed at higher ECAP passes. Continuous recrystallization phenomenon in microstructure was observed, where dislocation free crystallites with large misorientation to their surrounding matrix and smaller than the nuclei for discontinuous recrystallization were observed embodied in the matrix of deformed structure with high dislocation density. A two-step process was observed for the formation of these small crystallites, first the condensing of dislocation tangles into a narrow boundary, mostly low angle boundary; And second local migration (in sub-micrometer range) of short grain boundaries, in strong contrast to the dramatic migration of long large angle grain boundaries during discontinuous recrystallization to swallow the deformed matrix, was observed leading to vanish of small subgrains.

Observations oh Nucleation and Growth of Voids in Nickel

1970 ◽  
Vol 28 ◽  
pp. 414-415
Author(s):  
J. L. Brimhall ◽  
H. E. Kissinger ◽  
B. Mastel
Keyword(s):  
High Purity ◽  
Growth Stage ◽  
Elevated Temperatures ◽  
Early Growth ◽  
Nucleation And Growth ◽  
Pure Nickel ◽  
Different Temperatures ◽  
Total Fluence ◽  
Neutron Exposure ◽  
Growth Of Voids

Some information on the size and density of voids that develop in several high purity metals and alloys during irradiation with neutrons at elevated temperatures has been reported as a function of irradiation parameters. An area of particular interest is the nucleation and early growth stage of voids. It is the purpose of this paper to describe the microstructure in high purity nickel after irradiation to a very low but constant neutron exposure at three different temperatures.Annealed specimens of 99-997% pure nickel in the form of foils 75μ thick were irradiated in a capsule to a total fluence of 2.2 × 1019 n/cm2 (E > 1.0 MeV). The capsule consisted of three temperature zones maintained by heaters and monitored by thermocouples at 350, 400, and 450°C, respectively. The temperature was automatically dropped to 60°C while the reactor was down.

Comparative Labelling and Biokinetic Studies of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn)

1977 ◽  
Vol 16 (01) ◽  
pp. 30-35 ◽  
Author(s):  
N. Agha ◽  
R. B. R. Persson
Keyword(s):  
Complex Formation ◽  
Significant Influence ◽  
Room Temperature ◽  
Ph Value ◽  
Maximum Activity ◽  
Reduction Step ◽  
Labelling Yield ◽  
Different Temperatures ◽  
Kinetics Of

SummaryGelchromatography column scanning has been used to study the fractions of 99mTc-pertechnetate, 99mTcchelate and reduced hydrolyzed 99mTc in preparations of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn). The labelling yield of 99mTc-EDTA(Sn) chelate was as high as 90—95% when 100 μmol EDTA · H4 and 0.5 (Amol SnCl2 was incubated with 10 ml 99mTceluate for 30—60 min at room temperature. The study of the influence of the pH-value on the fraction of 99mTc-EDTA shows that pH 2.8—2.9 gave the best labelling yield. In a comparative study of the labelling kinetics of 99mTc-EDTA(Sn) and 99mTc- DTPA(Sn) at different temperatures (7, 22 and 37°C), no significant influence on the reduction step was found. The rate constant for complex formation, however, increased more rapidly with increased temperature for 99mTc-DTPA(Sn). At room temperature only a few minutes was required to achieve a high labelling yield with 99mTc-DTPA(Sn) whereas about 60 min was required for 99mTc-EDTA(Sn). Comparative biokinetic studies in rabbits showed that the maximum activity in kidneys is achieved after 12 min with 99mTc-EDTA(Sn) but already after 6 min with 99mTc-DTPA(Sn). The long-term disappearance of 99mTc-DTPA(Sn) from the kidneys is about five times faster than that for 99mTc-EDTA(Sn).

scholarly journals In Situ Grain Growth of Nanograined Magnetite under Ion Irradiation at Room Temperature and 500 ℃

2021 ◽  
Vol 27 (S1) ◽  
pp. 2640-2643
Author(s):  
Chris McRobie ◽  
Ryan Schoell ◽  
Tiffany Kaspar ◽  
Daniel Schreiber ◽  
Djamel Kaoumi
Keyword(s):  
Grain Growth ◽  
Room Temperature ◽  
Ion Irradiation

scholarly journals Temperature-Dependent Stimulated Emission Cross-Section in Nd3+:YLF Crystal

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 431
Author(s):  
Giorgio Turri ◽  
Scott Webster ◽  
Michael Bass ◽  
Alessandra Toncelli
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Room Temperature ◽  
Radiative Decay ◽  
Emission Cross Section ◽  
Spectroscopic Properties ◽  
Stimulated Emission ◽  
Different Temperatures ◽  
Stimulated Emission Cross Section ◽  
Semi Empirical

Spectroscopic properties of neodymium-doped yttrium lithium fluoride were measured at different temperatures from 35 K to 350 K in specimens with 1 at% Nd3+ concentration. The absorption spectrum was measured at room temperature from 400 to 900 nm. The decay dynamics of the 4F3/2 multiplet was investigated by measuring the fluorescence lifetime as a function of the sample temperature, and the radiative decay time was derived by extrapolation to 0 K. The stimulated-emission cross-sections of the transitions from the 4F3/2 to the 4I9/2, 4I11/2, and 4I13/2 levels were obtained from the fluorescence spectrum measured at different temperatures, using the Aull–Jenssen technique. The results show consistency with most results previously published at room temperature, extending them over a broader range of temperatures. A semi-empirical formula for the magnitude of the stimulated-emission cross-section as a function of temperature in the 250 K to 350 K temperature range, is presented for the most intense transitions to the 4I11/2 and 4I13/2 levels.

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