In Situ Investigation of Orientation Changes during Heating of Extruded AZ31

The orientation changes during heating of extruded AZ31 were investigated using synchrotron Xrays by in-situ experiments. The as-extruded sample shows a strong <10.0>-fiber texture which is generally observed after round extrusion. The initial <10.0>-fiber texture, in which the <10.0> direction of the hexagonal crystallites is parallel to extrusion direction, starts to change to <11.0>- fiber component at 300 °C. The orientation change rate shows an exponential relation to the heating temperature and the soaking time. The microstructure observations, prior and post heat treatment, indicate that the texture changes occur mainly during grain growth.

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In-situ investigation of alkalinity - denitrification coupling in the sediment - water column interface

10.5194/egusphere-egu2020-1555 ◽

2020 ◽

Author(s):

Mona Norbisrath

Keyword(s):

Water Column ◽

German Bight ◽

Anthropogenic Impacts ◽

Binding Capacity ◽

Quantitative Relationship ◽

Terminal Electron Acceptor ◽

The North ◽

In Situ Investigation ◽

In Situ Experiments

Abstract: EGU 2020Session: BG4.1: Biogeochemistry of coastal seas and continental shelves (Helmuth Thomas)Mona Norbisrath1, Kirstin D&#228;hnke1, Andreas Neumann1, Justus van Beusekom1, Nele Treblin1, Bryce van Dam1, Helmuth Thomas11Institute for Coastal Research, Helmholtz-Zentrum GeesthachtContact: [email protected]&#160;In-situ investigation of alkalinity - denitrification coupling in the sediment - water column interface&#160;As a shallow shelf sea, the North Sea is very vulnerable to anthropogenic impacts like rising CO2 concentrations, increasing nutrient inflows and coincident oxygen loss.Two important processes that determine the role of the coastal ocean as a net sink for anthropogenic CO2 are alkalinity and denitrification. Alkalinity, the acid binding capacity of the ocean, buffers natural and anthropogenic changes in the oceans&#8217; CO2 and pH system. Denitrification, an anaerobic microbial process in which organic matter is respired, uses NO3- instead of O2 as a terminal electron acceptor. Denitrification reduces NO3- to N2 and in turn produces alkalinity.Eutrophication, caused by leaching of excess fertilizer nutrients into coastal seas, leads to enhanced denitrification and therefore to enhanced alkalinity as well as an increased uptake of CO2. However, the quantitative relationship between denitrification and alkalinity production and its control under changing environmental conditions is yet to be determined.In the German Bight, denitrification is usually restricted to anoxic sediments. In this study, we therefore focus on in-situ experiments in the sediment - water column interface. Batch core incubations in combination with the isotope pairing technique (IPT) and labelled nitrate additions were used to detect denitrification and gauge its effect on alkalinity production during a cruise on RV Heincke (HE541) in September 2019 in the German Bight. To quantify denitrification, the production of all three N2 isotope species (28N2, 29N2 and 30N2) is measured using a membrane inlet mass spectrometer (MIMS). We expect an increase of denitrification rates with nitrate concentrations and incubation times, and we will quantify benthic denitrification. We will further evaluate the assumption of concurrent increases in alkalinity production and will investigate the benthic-pelagic coupling of these processes. Investigating the in-situ interaction of metabolic alkalinity and denitrification will give an estimation of the alkalinity impact on the reduction of anthropogenic CO2 in the atmosphere.&#160;

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In-situ investigation of ion-implantation effects on radiation-induced segregation in Ni-Al alloys

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100167408 ◽

1996 ◽

Vol 54 ◽

pp. 988-989

Author(s):

M.J. Giacobbe ◽

N.Q. Lam ◽

P.R. Okamoto ◽

N.J. Zaluzec ◽

J.F. Stubbins

Keyword(s):

Electron Beam ◽

National Laboratory ◽

Argonne National Laboratory ◽

Beam Diameter ◽

Total Electron ◽

Radial Segregation ◽

In Situ Investigation ◽

In Situ Experiments ◽

Radiation Induced

In-situ experiments using the HVEM (high voltage electron microscope)/Tandem accelerator facility at Argonne National Laboratory were performed to determine the effects of 400-keV Zr+ and 75-keV Ne+ implantation on electron radiation-induced segregation (RIS) in Ni-9at.%Al at 550°C and 450°C, respectively. The alteration of RIS kinetics by Ne implantation was studied at two different doses. A highly-focused 900-keV electron beam, which produces a radial defect flux away from the beam center, was used to induce segregation of Al atoms in the opposite direction via the inverse-Kirkendall effect. Within the irradiated zone, Al enrichment drives the formation of γ′-Ni3Al precipitates, and the radial segregation rate of Al was monitored by measuring the growth of the precipitate zone.When a thin film is subject to a focused, electron beam, a non uniform defect distribution is produced. The effective beam diameter, D∘, is defined by IT= I∘ (πD∘/2)2 where IT is the total electron current and I∘ is the peak electron flux.

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In Situ Investigation of the Oxidation Behaviour of Chemical Vapour Deposited Zr(C,N) Hard Coatings Using Synchrotron X–ray Diffraction

Coatings ◽

10.3390/coatings11030264 ◽

2021 ◽

Vol 11 (3) ◽

pp. 264

Author(s):

Florian Frank ◽

Michael Tkadletz ◽

Christian Saringer ◽

Andreas Stark ◽

Norbert Schell ◽

...

Keyword(s):

Chemical Vapour ◽

Oxidation Mechanism ◽

Oxidation Behaviour ◽

Ex Situ ◽

X Ray Diffraction ◽

X Ray ◽

Zro2 Phase ◽

In Situ Investigation ◽

In Situ Experiments

The oxidation behaviour of chemical vapour deposited ZrN, ZrC and ZrCN coatings was investigated using in-situ synchrotron X–ray diffraction (XRD). To obtain a precise analysis of the temperature–dependent phase evolution during oxidation, coating powders were annealed in air between 100 °C and 1000 °C. Simultaneously, 2D XRD patterns were recorded in ~2 °C increments, which were subsequently evaluated using parametric Rietveld refinement. The results were correlated with differential scanning calorimetry and thermogravimetric analysis measurements, to further illuminate the oxidation mechanism of each coating system. ZrCN exhibited the highest oxidation onset temperature, followed by ZrC and ZrN. Furthermore, ZrCN was completely oxidised at a temperature of ~720 °C, which was ~50–70 °C higher than for ZrN and ZrC. The in–situ experiments revealed a similar oxidation sequence for all three samples: first, tetragonal and/or cubic (c/t)–ZrO2 is formed, which subsequently transforms into the more stable monoclinic (m)–ZrO2 phase. ZrCN and ZrC showed a higher c/t–ZrO2 fraction than the ZrN sample at 1000 °C. Furthermore, ex–situ Raman and XRD investigations of the oxidised samples revealed the ongoing c/t–ZrO2 → m–ZrO2 phase transformation during cooling.

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In situ investigation of the primary recrystallization of alpha titanium in HVEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100110313 ◽

1978 ◽

Vol 36 (1) ◽

pp. 634-635

Author(s):

S. Naka ◽

R. Penelle ◽

R. Valle

Keyword(s):

Dimensional Analysis ◽

Texture Evolution ◽

Cold Work ◽

Three Dimensional ◽

Primary Recrystallization ◽

Thin Foils ◽

In Situ Investigation ◽

Grain Growth Model ◽

Alpha Titanium

The in situ experimentation technique in HVEM seems to be particularly suitable to clarify the processes involved in recrystallization. The material under investigation was unidirectionally cold-rolled titanium of commercial purity. The problem was approached in two different ways. The three-dimensional analysis of textures was used to describe the texture evolution during the primary recrystallization. Observations of bulk-annealed specimens or thin foils annealed in the microscope were also made in order to provide information concerning the mechanisms involved in the formation of new grains. In contrast to the already published work on titanium, this investigation takes into consideration different values of the cold-work ratio, the temperature and the annealing time.Two different models are commonly used to explain the recrystallization textures i.e. the selective grain growth model (Beck) or the oriented nucleation model (Burgers). The three-dimensional analysis of both the rolling and recrystallization textures was performed to identify the mechanismsl involved in the recrystallization of titanium.

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An in situ and ex situ TEM study of the formation of thin cobalt silicide films by molecular beam epitaxy on the silicon (100) surface

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010010648x ◽

1988 ◽

Vol 46 ◽

pp. 884-885

Author(s):

D. Loretto ◽

J. M. Gibson ◽

S. M. Yalisove ◽

R. T. Tung

Keyword(s):

Molecular Beam Epitaxy ◽

Molecular Beam ◽

Defect Density ◽

High Vacuum ◽

Ultra High Vacuum ◽

Ex Situ ◽

Metal Base ◽

In Situ Experiments ◽

Potential Applications

The cobalt disilicide/silicon system has potential applications as a metal-base and as a permeable-base transistor. Although thin, low defect density, films of CoSi2 on Si(111) have been successfully grown, there are reasons to believe that Si(100)/CoSi2 may be better suited to the transmission of electrons at the silicon/silicide interface than Si(111)/CoSi2. A TEM study of the formation of CoSi2 on Si(100) is therefore being conducted. We have previously reported TEM observations on Si(111)/CoSi2 grown both in situ, in an ultra high vacuum (UHV) TEM and ex situ, in a conventional Molecular Beam Epitaxy system.The procedures used for the MBE growth have been described elsewhere. In situ experiments were performed in a JEOL 200CX electron microscope, extensively modified to give a vacuum of better than 10-9 T in the specimen region and the capacity to do in situ sample heating and deposition. Cobalt was deposited onto clean Si(100) samples by thermal evaporation from cobalt-coated Ta filaments.

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Electron and ion irradiation-induced dissolution of mechanical twins in the intermetalic U3Si: An in situ HVEM study

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100155232 ◽

1989 ◽

Vol 47 ◽

pp. 652-653

Author(s):

Charles W. Allen ◽

Robert C. Birtcher

Keyword(s):

Elevated Temperatures ◽

Ion Irradiation ◽

Ion Beam ◽

National Laboratory ◽

Argonne National Laboratory ◽

Heavy Ion ◽

High Energy ◽

Mechanical Twinning ◽

In Situ Experiments

The uranium silicides, including U3Si, are under study as candidate low enrichment nuclear fuels. Ion beam simulations of the in-reactor behavior of such materials are performed because a similar damage structure can be produced in hours by energetic heavy ions which requires years in actual reactor tests. This contribution treats one aspect of the microstructural behavior of U3Si under high energy electron irradiation and low dose energetic heavy ion irradiation and is based on in situ experiments, performed at the HVEM-Tandem User Facility at Argonne National Laboratory. This Facility interfaces a 2 MV Tandem ion accelerator and a 0.6 MV ion implanter to a 1.2 MeV AEI high voltage electron microscope, which allows a wide variety of in situ ion beam experiments to be performed with simultaneous irradiation and electron microscopy or diffraction.At elevated temperatures, U3Si exhibits the ordered AuCu3 structure. On cooling below 1058 K, the intermetallic transforms, evidently martensitically, to a body-centered tetragonal structure (alternatively, the structure may be described as face-centered tetragonal, which would be fcc except for a 1 pet tetragonal distortion). Mechanical twinning accompanies the transformation; however, diferences between electron diffraction patterns from twinned and non-twinned martensite plates could not be distinguished.

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A computer-control program for TEM in situ fatigue experiments

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100155074 ◽

1989 ◽

Vol 47 ◽

pp. 620-621

Author(s):

Kenneth S. Vecchio ◽

John A. Hunt

Keyword(s):

Slow Crack Growth ◽

Computer Control ◽

Control Program ◽

Video Tape ◽

Computer Control System ◽

Transmission Electron ◽

In Situ Experiments ◽

Tremendous Amount ◽

And Control

In-situ experiments conducted within a transmission electron microscope provide the operator a unique opportunity to directly observe microstructural phenomena, such as phase transformations and dislocation-precipitate interactions, “as they happen”. However, in-situ experiments usually require a tremendous amount of experimental preparation beforehand, as well as, during the actual experiment. In most cases the researcher must operate and control several pieces of equipment simultaneously. For example, in in-situ deformation experiments, the researcher may have to not only operate the TEM, but also control the straining holder and possibly some recording system such as a video tape machine. When it comes to in-situ fatigue deformation, the experiments became even more complicated with having to control numerous loading cycles while following the slow crack growth. In this paper we will describe a new method for conducting in-situ fatigue experiments using a camputer-controlled tensile straining holder.The tensile straining holder used with computer-control system was manufactured by Philips for the Philips 300 series microscopes. It was necessary to modify the specimen stage area of this holder to work in the Philips 400 series microscopes because the distance between the optic axis and holder airlock is different than in the Philips 300 series microscopes. However, the program and interfacing can easily be modified to work with any goniometer type straining holder which uses a penrmanent magnet motor.

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