Effect of Annealing Temperature on Dislocation Loop Absorption And Evolution in Fe by Molecular Dynamics Study

2021 ◽  
Author(s):  
Pandong Lin ◽  
Junfeng Nie ◽  
Meidan Liu
Keyword(s):  
Molecular Dynamics ◽  
Dislocation Loop ◽  
Room Temperature ◽  
Annealing Temperature ◽  
Annealing Process ◽  
Basic Material ◽  
Absorption Process ◽  
Annealing Rate ◽  
Dynamics Method ◽  
Reactor Pressure

Abstract As the basic material in reactor pressure vessel (RPV), Fe endures amounts of irradiation in the entire lifetime. Many irradiation defects such as dislocation loop are generated which affect the macroscopic mechanical properties. In this paper, we use the molecular dynamics method to investigate the effect of annealing temperature on dislocation loop absorption and evolution. The annealing process contains four steps: At first, the temperature increases from room temperature (300K) to annealing temperature. The annealing temperature is set as 600K, 700K, 800K, 900K and 1000K respectively. Then the system maintains at annealing temperature for adequate time to evolve. After that, the temperature recovers to room temperature. Finally, the system evolves at room temperature to get the final configuration. The diameters of 1/2 <111> and <100> dislocation loop are 5.1 nm and 1.2 nm, respectively. The dimension of simulation cell is defined as 29.6nm × 20.2nm × 21.0nm with 1080455 atoms. Based on annealing simulation, we could obtain and analyze the microstructure evolution of dislocation loop. Apart from that, we also investigate the effect of annealing rate (4.29 K/ps, 6.00 K/ps, 10.00 K/ps and 30.00 K/ps) on the number of defect atoms and dislocation length during annealing process. Here under periodic boundary conditions the system is allowed to relax in all three directions independently. Results show that temperature has significant impact on the absorption and evolution of dislocation loop. However, temperature can improve the maximum values of defect atoms and accelerate absorption process from stage II to stage I when temperature is 900 K and 1000 K. In contrast, annealing rate has negligible impact on whether the number of defect atoms or dislocation length during the absorption and evolution of dislocation loop. These results are meaning for understanding the temperature effect on dislocation loop.

Structural Changes of UHV Deposited Titanium Thin Films in Presence of Oxygen Flow and Temperature

2011 ◽  
Vol 110-116 ◽  
pp. 1094-1098
Author(s):  
Haleh Kangarlou ◽  
Mehdi Bahrami Gharahasanloo ◽  
Akbar Abdi Saray ◽  
Reza Mohammadi Gharabagh
Keyword(s):  
Room Temperature ◽  
Structural Changes ◽  
Annealing Temperature ◽  
Annealing Process ◽  
Oxygen Flow ◽  
Glass Substrates ◽  
Annealing Temperatures ◽  
Titanium Thin Films ◽  
Deposition Angle ◽  
Ti Films

Ti films of same thickness, and near normal deposition angle, and same deposition rate were deposited on glass substrates, at room temperature, under UHV conditions. Different annealing temperatures as 393K, 493K and 593K with uniform 8 cm3/sec, oxygen flow, were used for producing titanium oxide layers. Their nanostructures were determined by AFM and XRD methods. Roughness of the films changed due to annealing process. The gettering property of Ti and annealing temperature can play an important role in the nanostructure of the films.

Deformation Mechanism of Diamond Nanocutting Single-Crystal Copper Using Molecular Dynamics Simulatio

2011 ◽  
Vol 239-242 ◽  
pp. 2775-2778
Author(s):  
Jia Xuan Chen ◽  
Ying Chun Liang ◽  
Xia Yu ◽  
Zhi Guo Wang ◽  
Zhen Tong
Keyword(s):  
Molecular Dynamics ◽  
Single Crystal ◽  
Cutting Force ◽  
Dislocation Loop ◽  
Deformation Mechanism ◽  
Molecular Dynamics Method ◽  
Parameter Method ◽  
Removal Mechanism ◽  
Single Crystal Copper ◽  
Dynamics Method

To study the removal mechanism of materials during nano cutting, molecular dynamics method is adopted to simulate single crystal copper nanomachining processes, and subsurface defects evolvements and chip forming regulation are analyzed by revised centro-symmetry parameter method and the ratios of the tangential cutting forceand the normal cutting force. The results show that there are different defects under different cutting depths. When cutting depths is shallower, there are dislocation loop nucleation in the subsurface of the workpiece beneath the tool; however, when the cutting depths is deeper, there are dislocations nucleation and slipping along {101} plane and (111) plane. In addition, both tangential cutting forceand the normal cutting force decrease as the cutting depths decreasing. When the ratios of the normal cutting force and the tangential cutting force is below 0.9, the chip will be formed.

STRUCTURE OF s-p BONDED METAL CLUSTERS WITH 8, 20 AND 40 VALENCE ELECTRONS

1992 ◽  
Vol 06 (23n24) ◽  
pp. 3681-3686
Author(s):  
Vijay Kumar
Keyword(s):  
Molecular Dynamics ◽  
Electronic Structure ◽  
Density Functional ◽  
Room Temperature ◽  
Metal Clusters ◽  
Molecular Dynamics Method ◽  
Valence Electrons ◽  
Bonding Characteristics ◽  
Atomic And Electronic Structure ◽  
Dynamics Method

From studies on some clusters of metals and semiconductors, there appear some similarities in the structure of clusters with a given number of atoms and having the number of valence electrons corresponding to a shell closing, Here we present results of the atomic and electronic structure of a few other clusters with 20 and 40 valence electrons, namely Sb 4, Sn 5 and Sb 8 using the density functional molecular dynamics method. We suggest that the similarities in the structure and deviation from them may help to understand bonding characteristics in clusters and its evolution to bulk behaviour. Our results on Sb 8 cluster are preliminary but indicate that above room temperature its structure is two weakly interacting tetrahedra which is in general agreement with the observation of predominently antimony tetramers at T>300 K.

Study on Direct Annealing Process of Hot-Rolled Plate

2011 ◽  
Vol 306-307 ◽  
pp. 535-538 ◽  
Author(s):  
Sheng Li Li ◽  
Xing Dong Peng ◽  
Yu Chen
Keyword(s):  
Room Temperature ◽  
Annealing Temperature ◽  
Annealing Process ◽  
Steel Grade ◽  
Rolled Plate ◽  
Measuring Instrument ◽  
R Value ◽  
Hot Rolled ◽  
Annealing Experiments ◽  
Room Temperature Tensile Test

To study the transmutation of organization and texture on direct annealing process of hot-rolled plate. Different annealing experiments were done in the lab. The annealed samples are from steel grade of SPHC. To check the organization of the annealed samples by optical microscopy, to measure grain size by Micro-image Analysis & process software. To measure the mechanical properties by the room temperature tensile test. To check AlN by TEM and EDX.To measure texture by texture measuring instrument, and the data was collected on a computer, using two-step calculation of ODF, measured with constant 45° section of graph. When annealing temperature of the samples reaches 875 °C or more, a relatively low strength , high n value, and high r value is received, but if the holding time is longer, grain coarsening occurs at the time,so the annealing temperature is not more than 925°C.When annealing temperature reaches 875 °C, AlN increased slightly, and the texture is not obvious.

Annealing Effect on the Thermoelectric Properties of Hot Extruded Bi2(Te0.94Se0.06)3+0.07wt%I+0.03wt%CuBr+0.02wt%Te Compound

2006 ◽  
Vol 15-17 ◽  
pp. 404-409
Author(s):  
Wang Kee Min ◽  
Sung Doo Hwang ◽  
Chang Ho Lee ◽  
Young Do Park ◽  
Yang Do Kim ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Annealing Temperature ◽  
Raw Materials ◽  
Extrusion Process ◽  
Annealing Process ◽  
Annealing Effect ◽  
Z Value

The n-type Bi2(Te0.94Se0.06)3 thermoelectric compound was prepared by the direct extrusion process using the powder as raw materials. Hot extruded specimens were annealed at 200°C and 350°C for 2hrs. The electrical conductivity, thermoelectric power and thermal conductivity of hot extruded and annealed specimens were measured at room temperature. The fractographs of the specimens showed that the grain size became coarser and a lot of porosities were generated during annealing process. The power factor value (PF) decreased with increasing the annealing temperature. The electric conductivity and thermal conductivity of the specimens also decreased with the increase of annealing temperature. This may be reasoned that the generated porosities affect the thermal conductivity of the specimens prepared in this study. The figure of merit (Z) value of the annealed specimens at 350°C was improved about 10%. The highest Z value of the specimens annealed at 350°C was 2.0 x 10-3/K among the prepared specimens.

Effect of Different Annealing Process for Microstructure and Properties of 1200MPa HSLA Steel

2015 ◽  
Vol 713-715 ◽  
pp. 2653-2657
Author(s):  
Yu Pei ◽  
Zhe Gao ◽  
Yi Liu ◽  
Shi Qian Zhao ◽  
Chang Yu Xu ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Room Temperature ◽  
Annealing Temperature ◽  
Hsla Steel ◽  
High Strength ◽  
Annealing Process ◽  
Air Cooling ◽  
Low Carbon ◽  
Slow Cooling ◽  
Microstructure And Properties

For C-Si-Mn low carbon HSLA(High Strength Low Alloyed) steel, the influence of microstructure and properties were researched on the different annealing processes. The result showed that the microstructure at room temperature of the steel were polygonal ferrite, island martensite and punctate bainite. With the increase of the annealing temperature, the content of martensite and bainiteincreased and the content of ferrite decreased. Accordingly, tensile strengthincreased from 1069MPa to 1498MPa, and the elongation decreased from 13.8% to 5.1%. With the increase of the overaging temperature, tensile strength decreased from 1315MPa to 1152MPa, and the elongationincreased from8.5% to9.8%. Finally, the optimum annealing process obtained that the annealing temperature was 820°C for 80s, slow cooling to 680°C, water quenching to room temperature, the overaging temperature was 280°C for 300s and air cooling to room temperature. The material obtained higher tensile strength and better elongation.

Computer Simulation of Thermal Annealing Effects on Self Implanted Silicon

1994 ◽  
Vol 373 ◽  
Author(s):  
G. DE Sandre ◽  
L. Colombo ◽  
D. Maric
Keyword(s):  
Molecular Dynamics ◽  
Thermal Annealing ◽  
Room Temperature ◽  
Annealing Temperature ◽  
Tight Binding ◽  
Defect Distribution ◽  
Amorphous Network ◽  
Different Temperatures ◽  
Annealing Effects

AbstractWe investigate the effects of thermal annealing on the structural, elastic and electronic properties of self implanted silicon by tight binding molecular dynamics. The irradiated samples, after a careful relaxation at room temperature, are annealed at different temperatures and for different times and, finally, their properties are carefully monitored during constant temperature simulations. We further provide a characterization of the chemical bonding in the amorphous network and show the evolution of the point defect distribution against maximum annealing temperature.

Rapid Thermal Annealing of Al and P Implanted Single Crystal Beta Silicon Carbide Thin Films

1985 ◽  
Vol 52 ◽  
Author(s):  
J. A. Edmond ◽  
H. J. Kim ◽  
R. F. Davis
Keyword(s):  
Thin Films ◽  
Thermal Annealing ◽  
Rapid Thermal Annealing ◽  
Room Temperature ◽  
Annealing Temperature ◽  
Compound Semiconductors ◽  
Annealing Process ◽  
Capacitance Voltage ◽  
P Type ◽  
Sic Films

ABSTRACTIon implantation of 27Al+ and 31p+ ions into monocrystalline s-SiC films was conducted in order to acquire p-type and n-type conducting layers, respectively. Implant energies ranging from 110 to 190 keV and fluences from 7 × 1013 to 9 × 1014 cm-2 were used. In order to activate each dopant specie, rapid thermal annealing (RTA) was employed. A decrease in sheet resistance with increasing annealing temperature for both type layers was observed up to 1800°C. After annealing at this highest temperature for 300 s in 1 atm. Ar, the percent of activated and ionized n-type and p-type dopant was ≅20% and ≅0.5%, respectively, as determined by room temperature capacitance-voltage measurements. Recrystallization of both heavily damaged and amorphized layers occurred as a result of the use of the aforementioned annealing process. Unlike SPE regrowth in other compound semiconductors, no microtwins were present in the regrown bulk as observed by XTEM. SIMS analyses also showed that there was essentially no redistribution of P and moderate redistribution of Al from the corresponding as-implanted profiles after annealing.

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