In situ TEM thermal annealing of high purity Fe10wt%Cr alloy thin foils implanted with Ti and O ions

AbstractGlass-forming ability, thermal stability and nucleation behavior of a Pd40Cu30Ni10P20 alloy prepared using a high purity polycrystalline phosphorus are investigated. The critical cooling rate for glass formation for the high purity alloy is the same as that for the previous result, but the improvement of undercooling reaches about 80 K as compared with the fluxed ordinary alloy. In comparison with the non-fluxed alloy, the solidified structure of the present highly purified alloy is significantly different. The non-fluxed sample shows the characteristic “island-like” structure consisted of acicular fcc-Pd2Ni2P solid solution and Cu3Pd intermetallic compound. These acicular phases appear to be caused by the growth of quenched-in nuclei. In the isothermal experiment, nucleus density exhibits time dependence even at 683 K near the nose temperature. It is assumed that the crystallization behavior for the highly purified alloy is closer to homogeneous nucleation from quenched-in nuclei dominant behavior. In order to investigate the nucleation behavior, in-situ TEM observation was carried out. Spherical Pd15P2 particle with a diameter about 15 nm is observed, and this spherical region repeats generation and annihilation during isothermal annealing. The reason for the high glass-forming ability is discussed on the basis of the obtained results.

Download Full-text

In-Situ TEM Study of Plastic Stress Relaxation Mechanisms and Interface Effects in Metallic Films

MRS Proceedings ◽

10.1557/proc-875-o9.1 ◽

2005 ◽

Vol 875 ◽

Cited By ~ 6

Author(s):

Marc Legros ◽

Gerhard Dehm ◽

T. John Balk

Keyword(s):

Thin Films ◽

High Strength ◽

Dislocation Motion ◽

Dislocation Nucleation ◽

Film Stress ◽

In Situ Tem ◽

Metallic Films ◽

Cross Sectional ◽

Thin Foils

AbstractTo investigate the origin of the high strength of thin films, in-situ cross-sectional TEM deformation experiments have been performed on several metallic films attached to rigid substrates. Thermal cycles, comparable to those performed using laser reflectometry, were applied to thin foils inside the TEM and dislocation motion was recorded dynamically on video. These observations can be directly compared to the current models of dislocation hardening in thin films. As expected, the role of interfaces is crucial, but, depending on their nature, they can attract or repel dislocations. When the film/interface holds off dislocations, experimental values of film stress match those predicted by the Nix-Freund model. In contrast, the attracting case leads to higher stresses that are not explained by this model. Two possible hardening scenarios are explored here. The first one assumes that the dislocation/interface attraction reduces dislocation mobility and thus increases the yield stress of the film. The second one focuses on the lack of dislocation nucleation processes in the case of attracting interfaces, even though a few sources have been observed in-situ.

Download Full-text

In-Situ TEM Deformation Studies of Dislocation Generation and Motion in High-Purity MO Single Crystals

MRS Proceedings ◽

10.1557/proc-578-113 ◽

1999 ◽

Vol 578 ◽

Author(s):

M. Jouiad ◽

B. W. Lagow ◽

I. M. Robertson ◽

D. H. Lassila

Keyword(s):

Single Crystals ◽

Screw Dislocation ◽

High Purity ◽

In Situ Tem ◽

Dislocation Source ◽

Dislocation Generation ◽

Transmission Electron ◽

Dislocation Tangle ◽

Source Operation

AbstractThe generation and motion of dislocations in high-purity single crystals of Mo have been observed in real time by deforming electron-transparent samples in-situ in a transmission electron microscope. At 300 K and at low levels of stress, a novel dislocation source was observed that generated a long, straight screw dislocation. The source was a dislocation tangle that existed in the annealed material. An edge dislocation emerged from the tangle, trailing behind it the screw dislocation. These screw dislocations were immobile at this stress level. At higher stresses, the same dislocation tangle generated many dislocations, but now by a pole mechanism. The nature of these tangles and the source operation mechanisms will be described.

Download Full-text

In situ Tensile Testing of Nanoscale Freestanding Thin Films Inside a Transmission Electron Microscope

Journal of Materials Research ◽

10.1557/jmr.2005.0220 ◽

2005 ◽

Vol 20 (7) ◽

pp. 1769-1777 ◽

Cited By ~ 68

Author(s):

M.A. Haque ◽

M.T.A. Saif

Keyword(s):

Stress Measurement ◽

Crystallographic Analysis ◽

Uniaxial Tensile ◽

In Situ Tem ◽

Sensors And Actuators ◽

Displacement Sensors ◽

Thin Foils ◽

Transmission Electron ◽

Tensile Experiment

The unique capability of rendering opaque specimens transparent with atomic resolution makes transmission electron microscopy (TEM) an indispensable toolfor microstructural and crystallographic analysis of materials. Conventional TEM specimens are placed on grids about 3 mm in diameter and 10–100 μm thick. Such stringent size restriction has precluded mechanical testing inside the TEM chamber.So far, in situ testing of nanoscale thin foils has been mostly qualitative. Micro-electro-mechanical systems (MEMS) offer an unprecedented level of miniaturization to realize sensors and actuators that can add TEM visualization to nano-mechanical characterization. We present a MEMS-based uniaxial tensile experiment setup that integrates nanoscale freestanding specimens with force and displacement sensors, which can be accommodated by a conventional TEM straining stage. In situ TEM testing on 100-nm-thick freestanding aluminum specimens (with simultaneous stress measurement) show limited dislocation activity in the grain interior and consequent brittle mode of fracture. Plasticity at this size scale is contributed by grain boundary dislocations and partial dislocations.

Download Full-text

Suppression of Thermal Grain Growth in Nickel by Prior Electron Irradiation

MRS Proceedings ◽

10.1557/proc-316-217 ◽

1993 ◽

Vol 316 ◽

Author(s):

Yuzun Gao ◽

Charles W. Allen ◽

R. C. Bitrtcher

Keyword(s):

Electron Beam ◽

Grain Growth ◽

Thermal Annealing ◽

Electron Energy ◽

Electron Irradiation ◽

Ion Beam ◽

In Situ Tem ◽

Anomalous Effect ◽

Beam Injection

ABSTRACTAn anomalous effect of electron irradiation on thermal grain growth in Ni has been observed using in situ TEM. Grain growth during thermal annealing was suppressed in areas irradiated with electrons. Grain growth suppression required a minimum electron energy between 100 and 200 keV. This alteration of thermal grain growth is attributed to electron beam injection of a surface contaminant such as carbon. This work points out that care must be exercised in the execution and evaluation of in situ TEM or ion beam experiments that deal with microstructural changes which are highly compositionally sensitive.

Download Full-text

In-situ TEM studies of ion-irradiation induced bubble development and mechanical deformation in model nuclear materials

MRS Proceedings ◽

10.1557/opl.2014.221 ◽

2014 ◽

Vol 1645 ◽

Cited By ~ 3

Author(s):

S E Donnelly ◽

G Greaves ◽

J A Hinks ◽

C J Pawley ◽

M-F Beaufort ◽

...

Keyword(s):

Ion Irradiation ◽

Foil Thickness ◽

In Situ Tem ◽

Accelerator Facility ◽

Dimensional Changes ◽

Thin Foils ◽

Ion Accelerator ◽

Thin Electron ◽

Singly Charged

ABSTRACTThe MIAMI* facility at the University of Huddersfield is one of a number of facilities worldwide that permit the ion irradiation of thin foils in-situ in a transmission electron microscope. MIAMI has been developed with a particular focus on enabling the in-situ implantation of helium and hydrogen into thin electron transparent foils, necessitating ion energies in the range 1 – 10 keV. In addition, however, ions of a variety of species can be provided at energies of up to 100 keV (for singly charged ions), enabling studies to focus on the build up of radiation damage in the absence or presence of implanted gas.This paper reports on a number of ongoing studies being carried out at MIAMI, and also at JANNuS (Orsay, France) and the IVEM / Ion Accelerator Facility (Argonne National Lab, US). This includes recent work on He bubbles in SiC and Cu; the former work concerned with modification to bubble populations by ion and electron beams and the latter project concerned with the formation of bubble super-lattices in metals.A study is also presented consisting of experiments aimed at shedding light on the origins of the dimensional changes known to occur in nuclear graphite under irradiation with either neutrons or ions. Single crystal graphite foils have been irradiated with 60 keV Xe ions in order to create a non-uniform damage profile throughout the foil thickness. This gives rise to varying basal-plane contraction throughout the foil resulting in almost macroscopic (micron scale) deformation of the graphite. These observations are presented and discussed with a view to reconciling them with current understanding of point defect behavior in graphite.*Microscope and Ion Accelerator for Materials Investigations

Download Full-text

In situ studies on grain boundary migration in ceria-stabilized TZP

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100174096 ◽

1990 ◽

Vol 48 (4) ◽

pp. 192-193

Author(s):

Herbert K Schmid

Keyword(s):

Grain Boundary ◽

Grain Boundaries ◽

Room Temperature ◽

Boundary Migration ◽

Tetragonal Zirconia ◽

In Situ Tem ◽

Grain Boundary Migration ◽

Thin Foils ◽

Prepared State

Tetragonal zirconia polycrystals (TZP) have become of interest due to their exceptionally good combination of mechanical properties. In a previous study the microstructure/microchemistry of grain boundaries (GBs) in CeO2 stabilized ZrO2 (Ce-TZP) was investigated and evidence was found on the existence of vitreous ana crystalline intergranular phases in these ceramics. Recently, the observation of wavy GBs in ceria-zirconia was reported. This phenomenon was attributed to diffusion-induced grain boundary migration (DIGM). In the present work, the in-situ TEM observation of GB migration in Ce-TZP, nominally at room temperature, is reported.Thin foils for TEM observations were prepared from a Ce-TZP ceramic nominally composed of 90 mol% ZrO2 plus 10 mol% CeO2 and were examined in a Philips EM 420 analytical STEM, operated at 120 kV. Grain boundaries were observed to migrate in specimen areas exposed to extensive electron irradiation during TEM experiments. The micrograph in Fig. 1 shows a BF image of a triple grain junction (TJ) area in the as-prepared state.

Download Full-text

In situ TEM observation of tensile deformation in high-purity titanium after a single compression stroke

Scripta Metallurgica ◽

10.1016/0036-9748(89)90450-x ◽

1989 ◽

Vol 23 (4) ◽

pp. 553-556 ◽

Cited By ~ 2

Author(s):

Zhang Jieping ◽

Gu Haicheng ◽

Zhou Huiju ◽

Campbell Laird

Keyword(s):

High Purity ◽

Tensile Deformation ◽

In Situ Tem ◽

Compression Stroke ◽

Purity Titanium

Download Full-text

Effets of surfaces on precipitate morphology in irradiated thin foils

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100110416 ◽

1978 ◽

Vol 36 (1) ◽

pp. 654-655

Author(s):

D.I. Potter ◽

A. Taylor

Keyword(s):

Ion Irradiation ◽

Dark Field Image ◽

Thin Foil ◽

Dark Field ◽

Al Alloy ◽

Bright Field Image ◽

Dislocation Loops ◽

Precipitate Morphology ◽

Thin Foils

Thermal aging of Ni-12.8 at. % A1 and Ni-12.7 at. % Si produces spatially homogeneous dispersions of cuboidal γ'-Ni3Al or Ni3Si precipitate particles arrayed in the Ni solid solution. We have used 3.5-MeV 58Ni+ ion irradiation to examine the effect of irradiation during precipitation on precipitate morphology and distribution. The nearness of free surfaces produced unusual morphologies in foils thinned prior to irradiation. These thin-foil effects will be important during in-situ investigations of precipitation in the HVEM. The thin foil results can be interpreted in terms of observations from bulk irradiations which are described first.Figure 1a is a dark field image of the γ' precipitate 5000 Å beneath the surface(∿1200 Å short of peak damage) of the Ni-Al alloy irradiated in bulk form. The inhomogeneous spatial distribution of γ' results from the presence of voids and dislocation loops which can be seen in the bright field image of the same area, Fig. 1b.

Download Full-text

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.

Download Full-text