scholarly journals In Situ Observation on the Effects of Prior Martensite Formation on Nanostructured Low–Temperature Bainite Transformation

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 818 ◽  
Author(s):  
Wen Zhou ◽  
Tingping Hou ◽  
Lang Tao ◽  
Kaiming Wu
Keyword(s):  
Isothermal Holding ◽  
Martensite Plate ◽  
Parent Phase ◽  
Longitudinal Direction ◽  
In Situ Observation ◽  
Martensite Formation ◽  
Transformation Behavior ◽  
Lateral Direction ◽  
In Situ Observations

Nanobainite transformation behavior was comparably studied using in situ observations for two heat treatments: With and without partial quenching before isothermal holding at 300 °C. It was found that the prior martensite formation significantly accelerated the rate of the subsequent nanobainite transformation. Bainitic laths formed adjacent to a prior martensite plate and grew up to austenites. Bainite phase also formed both at the grain boundaries of the parent phase and inside the grains. Regarding the growth mode, bainite grows along the longitudinal direction and hardly grows along the lateral direction.

scholarly journals In Situ Investigation of Grain Evolution of 300M Steel in Isothermal Holding Process

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1862 ◽  
Author(s):  
Rongchuang Chen ◽  
Zhizhen Zheng ◽  
Jianjun Li ◽  
Ning Li ◽  
Fei Feng
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Grain Growth ◽  
Isothermal Holding ◽  
In Situ Observation ◽  
Initial Stage ◽  
300M Steel ◽  
Average Grain Size ◽  
In Situ Observations

The relationships between initial microstructures, process parameters, and grain evolutions in isothermal holdings have drawn wide attention in recent years, but the grain growth behaviors of 300M steel were not well understood, resulting in a failure in precise microstructure controlling in heat treatment. In this work, in situ observations were carried out to characterize the grain evolutions of 300M steel with varying holding time, holding temperatures, and initial microstructures. The intriguing finding was that the grain refinement by austenization of 300M steel was followed by a dramatic grain growth in the initial stage of holding (≤~600 s), and with increasing time (~600–7200 s), the average grain size appeared to have a limit value at specific temperatures. The austenization process accelerated the grain growth by generating large quantity of grain boundaries at the initial stage of holdings, and the growth rate gradually slowed down after holding for ~600 s because the driven force was weakened due to the reduction of grain boundary energy. The initial structure and the initial grain size of 300M steel had no obvious influences on the grain size evolutions. The mechanisms of grain growth were analyzed based on in situ observations and transmission electron microscope (TEM) characterizations. A grain evolution model considering the grain boundary migration of 300M steel was established for the isothermal holding process. Good agreement was obtained between the in situ observation results and the model calculation results. This investigation aimed to understand fundamentally the grain evolutions of 300M steel in the isothermal holding process.

scholarly journals Pelagic deep-sea fauna observed on video transects in the southern Norwegian Sea

Polar Biology ◽  
2021 ◽  
Author(s):  
Philipp Neitzel ◽  
Aino Hosia ◽  
Uwe Piatkowski ◽  
Henk-Jan Hoving
Keyword(s):  
First Record ◽  
Observation System ◽  
In Situ Observation ◽  
Norwegian Sea ◽  
Video Recordings ◽  
In Situ Observations ◽  
Abundance And Distribution ◽  
Oceanic Food Webs ◽  
Deep Sea Fauna

AbstractObservations of the diversity, distribution and abundance of pelagic fauna are absent for many ocean regions in the Atlantic, but baseline data are required to detect changes in communities as a result of climate change. Gelatinous fauna are increasingly recognized as vital players in oceanic food webs, but sampling these delicate organisms in nets is challenging. Underwater (in situ) observations have provided unprecedented insights into mesopelagic communities in particular for abundance and distribution of gelatinous fauna. In September 2018, we performed horizontal video transects (50–1200 m) using the pelagic in situ observation system during a research cruise in the southern Norwegian Sea. Annotation of the video recordings resulted in 12 abundant and 7 rare taxa. Chaetognaths, the trachymedusaAglantha digitaleand appendicularians were the three most abundant taxa. The high numbers of fishes and crustaceans in the upper 100 m was likely the result of vertical migration. Gelatinous zooplankton included ctenophores (lobate ctenophores,Beroespp.,Euplokamissp., and an undescribed cydippid) as well as calycophoran and physonect siphonophores. We discuss the distributions of these fauna, some of which represent the first record for the Norwegian Sea.

scholarly journals Imaging the Polymorphic Transformation in a Single Cu6Sn5 Grain in a Solder Joint

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2229 ◽  
Author(s):  
Flora Somidin ◽  
Hiroshi Maeno ◽  
Xuan Tran ◽  
Stuart D. McDonald ◽  
Mohd Mohd Salleh ◽  
...  
Keyword(s):  
Solder Joint ◽  
Polymorphic Transformation ◽  
Structural Evolution ◽  
Real Space ◽  
Transformation Behavior ◽  
New Approach ◽  
Transmission Electron ◽  
Contrast Pattern ◽  
In Situ Observations

In-situ observations of the polymorphic transformation in a single targeted Cu6Sn5 grain constrained between Sn-0.7 wt % Cu solder and Cu-Cu3Sn phases and the associated structural evolution during a solid-state thermal cycle were achieved via a high-voltage transmission electron microscope (HV-TEM) technique. Here, we show that the monoclinic η′-Cu6Sn5 superlattice reflections appear in the hexagonal η-Cu6Sn5 diffraction pattern upon cooling to isothermal 140 °C from 210 °C. The in-situ real space imaging shows that the η′-Cu6Sn5 contrast pattern is initiated at the grain boundary. This method demonstrates a new approach for further understanding the polymorphic transformation behavior on a real solder joint.

New record of Munidopsis taiwanica (Decapoda, Anomura) from a mud volcano field in the Mariana Trench, with in-situ observations on habitat

Crustaceana ◽  
2018 ◽  
Vol 91 (3) ◽  
pp. 363-373 ◽  
Author(s):  
Dong Dong ◽  
Xinzheng Li
Keyword(s):  
New Record ◽  
Mud Volcano ◽  
In Situ Observation ◽  
Mariana Trench ◽  
Squat Lobster ◽  
The World ◽  
In Situ Observations ◽  
Seafloor Sediments ◽  
Squat Lobsters

Squat lobsters are prevalent in chemosynthetic environments but have been insufficiently studied in mud volcano habitats. An abyssal species,Munidopsis taiwanicaOsawa, Lin & Chan, 2008 was recently collected in a mud volcano field in the Mariana Trench at a depth greater than 5000 m, which represents a new distributional record. Its diagnostic characters are presented in this study. In-situ observation suggested thatM. taiwanicawas closely associated with this chemosynthetic environment and probably exhibited camouflage behaviour by attaching seafloor sediments onto its body.Munidopsis taiwanicais the first confirmed species of squat lobster found in the mud volcano environment, and currently represents the deepest record (5491 m) of squat lobsters in the world.

scholarly journals On the Feasibility of In-Venue Observations of Electronic Gaming Machine Gamblers and Game Characteristics

2017 ◽  
Author(s):  
Jason Landon ◽  
Katie Palmer Du Preez ◽  
Maria Bellringer ◽  
Max Abbott ◽  
Amanda Roberts
Keyword(s):  
New Zealand ◽  
Observational Studies ◽  
In Situ Observation ◽  
Harm Minimization ◽  
Observable Effect ◽  
In Situ Observations ◽  
Gaming Machine ◽  
Gaming Machines ◽  
Valid Information

Detailed observational studies of undisturbed gambler behaviour in venues are rare, especially when the focus is on continuous gambling such as electronic gaming machines (EGMs). EGMs are the main source of harmful gambling in New Zealand and all EGMs in New Zealand now include a mandatory pop-up message feature. The present study reports on 48 hours of in situ observations of EGM gamblers in casino and non-casino (pub) venues in New Zealand. We sought to establish whether relatively detailed observations of EGM features and gambler behaviour in venues were possible. The EGM feature that we focused on were pop-up messages, given their harm-minimization potential and the relative ease with which they can be observed. However, other EGM features were also documented, along with descriptive accounts of associated gambler behaviour. The results establish that relatively detailed (quantitative or qualitative) observational data can be collected in venues by using smart phones. The data showed that pop-up messages were generally attended to, but had little observable effect on gambler behaviour in venues. Direct in situ observation of gamblers can provide ecologically valid information to complement more common experimental and survey-based approaches. Suggestions are made for developing the procedure.Les études d’observation détaillée in situ sur le comportement non perturbé de joueurs sont rares, surtout si on met l’accent sur le jeu continu, comme avec les appareils de jeux électroniques. En Nouvelle-Zélande, ces appareils sont la principale source de jeux compulsifs, et tous les appareils dans ce pays incluent dorénavant une fonctionnalité obligatoire de message contextuel. La présente étude fait état de 48 heures d’observation in situ de joueurs sur appareils dans des casinos ou d’autres lieux (bars) en Nouvelle-Zélande, et on a cherché à déterminer s’il était possible de faire des observations relativement détaillées des caractéristiques et du comportement de joueurs dans ces lieux. On a mis l’accent sur la fonctionnalité des messages contextuels pour analyser leur potentiel de diminuer des méfaits et leur relative facilité à les observer. On a aussi consigné d’autres fonctionnalités d’appareils de jeu, ainsi que des comptes-rendus descriptifs du comportement des joueurs associés. Les résultats montrent que l’on peut recueillir des données d’observation in situ relativement détaillées (quantitatives ou qualitatives) à l’aide de téléphones intelligents. Les données montrent que les messages contextuels ont généralement été pris en compte, mais qu’ils ont eu peu d’effet observable sur le comportement des joueurs. L’observation directe de joueurs peut fournir des informations écologiquement valables pour appuyer les approches expérimentales communes par sondage. On y fait aussi quelques suggestions pour mettre en œuvre une procédure.

scholarly journals In situ observation of cracking and self-healing of solid electrolyte interphases during lithium deposition

2020 ◽  
Author(s):  
Tingting Yang ◽  
Hui Li ◽  
Yongfu Tang ◽  
Jingzhao Chen ◽  
Hongjun Ye ◽  
...  
Keyword(s):  
Solid Electrolyte ◽  
Solid Electrolyte Interphase ◽  
Dendrite Growth ◽  
In Situ Observation ◽  
Self Healing ◽  
Directional Growth ◽  
Transmission Electron ◽  
In Situ Observations ◽  
Li Batteries

Abstract The growth of lithium (Li) whiskers is detrimental to Li batteries. However, it remains a challenge to directly track Li whisker growth. Here we report in situ observations of electrochemically induced Li deposition under a CO2 atmosphere inside an environmental transmission electron microscope. We find that the morphology of individual Li deposits is strongly influenced by the competing processes of cracking and self-healing of the solid electrolyte interphase (SEI). When cracking overwhelms self-healing, the directional growth of Li whiskers predominates. In contrast, when self-healing dominates over cracking, the isotropic growth of round Li particles prevails. The Li deposition rate and SEI constituent can be tuned to control the Li morphologies. We reveal a new “weak-spot” mode of Li dendrite growth, which is attributed to the operation of the Bardeen-Herring growth mechanism in the whisker’s cross section. This work has implications for the control of Li dendrite growth in Li batteries.

In Situ Observation of Microstructure Evolution in Low Carbon Bainite Steels Isothermally Held Below A1 Temperature

2010 ◽  
Vol 654-656 ◽  
pp. 126-129 ◽  
Author(s):  
Rui Zhang ◽  
Shan Wu Yang ◽  
Chao Sun ◽  
Xin Lai He
Keyword(s):  
Isothermal Holding ◽  
Bainitic Ferrite ◽  
Polygonal Ferrite ◽  
In Situ Observation ◽  
Low Carbon ◽  
Thermal Disturbance ◽  
Low Carbon Bainite ◽  
Equilibrium Phases ◽  
Scanning Electron

The dominant microstructures in low carbon bainite steels such as bainitic ferrite are non-equilibrium phases, which will tend to evolve into equilibrium phases when the steels are subjected to thermal disturbance. In-situ observation by optical and scanning electron microscopy was carried out in this investigation to track the evolution when the steels were isothermally held below A1 temperature. It is found that the primary polygonal ferrite grows slowly during isothermal holding, while bainitic ferrite changes rapidly into polygonal ferrite. Self-tempered bainitic ferrite would recover further and recrystallize. The lower the concentration product of carbon and niobium, the faster is the evolution.

Low Temperature Synthesis of Carbon Nanotube on Si substrate Using Alcohol Gas Source in High Vacuum

2007 ◽  
Vol 1057 ◽  
Author(s):  
Takahiro Maruyama ◽  
Kenji Tanioku ◽  
Shigeya Naritsuka
Keyword(s):  
Low Temperature ◽  
Growth Temperature ◽  
Intensity Ratio ◽  
High Vacuum ◽  
In Situ Observation ◽  
Si Substrate ◽  
Growth Pressure ◽  
Gas Source ◽  
In Situ Observations

ABSTRACTConventional alcohol catalytic chemical vapor deposition (ACCVD) growth of carbon nanotubes (CNTs) have been carried out under ambient gases from 103 to105 Pa. These ambient gas pressures have prevented in situ observations using an electron beam during CNT growth, such as scanning electron microscopy (SEM), scanning tunneling microscopy (STM). Therefore, in order to realize the in situ observations and to clarify the growth mechanism of nanotube, CNT growth in a high vacuum is essential. In addition, the effects of residual gases also may be avoided in the growth under high vacuum. In this study, we carried out CNT growth under high vacuum using an alcohol gas source in an ultrahigh vacuum (UHV) chamber and we achieved CNT growth below 400°C without any excitation processes of carbon source. After deposition of Co catalyst of 1 nm in thickness on SiO2/Si substrate, ethanol gas was supplied to the substrate surface through a stainless steel nozzle in the UHV chamber. The growth temperature was monitored by a pyrometer during the growth, and set between 350 and 900°C. The supply of ethanol gas was controlled by monitoring an ambient pressure, which was varied from 1 ∼10-1 to 1 ∼10-4 Pa. The grown CNTs were characterized by SEM and Raman spectroscopy. The G/Si intensity ratio reached its maximum at 700°C, when the pressure was 1 ∼10-1 Pa. The maximum point of the G/Si peak intensity shifted to a lower temperature as the growth pressure decreased. When the pressure was 1 ∼10-4 Pa, the G/Si intensity ratio reached its maximum at 400°C, at which clear RBM peaks were observed in the Raman spectrum. From the RBM peaks, the CNT diameters were estimated to be between 0.9 to 1.7 nm, and CNTs of 1.2-1.4 nm in diameter were dominant at 1 ∼10-1 Pa, whereas thinner CNTs (diameter is below 1.0 nm) were increased with the reduction of the pressure. Our largest G/D ratio was about 40 for the sample grown at 1 ∼10-1 Pa, which is considerably larger than the reported value for the CNTs grown under low pressure. From these results, we conclude that the reduction of the growth pressure lowers the growth temperature. This technique can be applied to in situ observation, and may also be useful for low temperature growth of CNTs, which opens new possibilities for the fabrication of CNT based nanodevices.

scholarly journals The In Situ Observation of Phase Transformations During Intercritical Annealing of a Medium Manganese Advanced High Strength Steel by High Energy X-Ray Diffraction

2021 ◽  
Vol 8 ◽  
Author(s):  
Xiaohua Hu ◽  
Josh J. Mueller ◽  
Xin Sun ◽  
Emmanuel De Moor ◽  
John G. Speer ◽  
...  
Keyword(s):  
Intercritical Annealing ◽  
Isothermal Holding ◽  
High Energy ◽  
Manganese Steel ◽  
Temperature Deformation ◽  
In Situ Observation ◽  
X Ray Diffraction ◽  
Equilibrium Conditions ◽  
X Ray

Microstructural changes during thermal processing of a medium manganese steel containing (in wt%) 0.19C and 4.39 Mn were evaluated in situ with a high energy X-ray diffraction system (HEXRD). Samples with an initial fully martensitic microstructure were heated to intercritical annealing (IA) temperatures of 600 or 650°C, held for 30 min, and cooled to room temperature. Diffraction data were analyzed to determine the variations in austenite and ferrite phase fractions and phase lattice constants throughout the ICA cycles. On heating, the 2 vol. pct of austenite present in the starting microstructure decomposed, and cementite precipitation then occurred. During isothermal holding, the austenite fraction increased, up to 20% for the sample annealed at 650°C. The measured austenite fractions were less than those calculated by Thermo-Calc for equilibrium conditions, indicating that the 30-min hold time was insufficient to achieve near-equilibrium conditions. Observed changes in lattice parameters during isothermal holding were interpreted to reflect composition changes due to redistribution of the C and Mn between austenite and ferrite. The results are discussed in relation to the potential for controlling austenite stability during ambient temperature deformation.

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