scholarly journals Micromechanical testing of oxidised grain boundaries in Ni Alloy 600

2013 ◽  
Vol 1514 ◽  
pp. 119-124 ◽  
Author(s):  
Alisa Stratulat ◽  
Steve G. Roberts
Keyword(s):  
Fracture Toughness ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Alloy 600 ◽  
Average Value ◽  
Micromechanical Testing ◽  
Ni Alloy ◽  
Primary Water

ABSTRACTMicromechanical testing of focused ion beam (FIB) machined cantilevers was used to study oxidised grain boundaries in Ni-alloy 600. The Ni-alloy 600 samples were exposed in simulated PWR primary water at 325°C for 4500h with a hydrogen partial pressure of 30kPa. The FIB was used to machine small cantilever beams at the selected sites in the Ni alloy 600, cut so that the beam contained a selected grain boundary close to the built-in end. The FIB was also used to make a pre-crack, 700 nm deep, on the grain boundary. Cantilevers were loaded at the free end using a nanoindenter. Cantilevers milled in the un-oxidised sample yielded, and did not fracture. The specimens containing oxidised grain boundaries fractured at the boundary after small amounts of plasticity. Load vs. displacement data were used to calculate the fracture toughness of the oxidised grain boundaries. The fracture toughness associated with fracture of grain boundary oxide for these cantilevers was in the range 0.73-1.82MPa (m)1/2, with an average value of 1.3MPa (m)1/2. We believe this to be the first time the fracture toughness of an oxidised grain boundary has been determined.

The evaluation of the composition dependence of fracture toughness of Al3Nb alloys by using micro-size fracture testing

MRS Advances ◽  
2017 ◽  
Vol 2 (26) ◽  
pp. 1405-1410
Author(s):  
Nobuhiro Matsuzaki ◽  
Ken-ichi Ikeda ◽  
Seiji Miura ◽  
Nobuaki Sekido ◽  
Takahito Ohmura
Keyword(s):  
Fracture Toughness ◽  
Single Crystal ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Two Phase ◽  
Fracture Testing ◽  
Average Value ◽  
Chevron Notch ◽  
Polycrystalline Alloys ◽  
Oxidation Resistant

ABSTRACTAl3Nb is known as a high oxidation resistant material, while it is quite brittle. As the fracture toughness of Al3Nb single crystal and its dependence on the composition are not obtained, the micro-sized fracture testing proposed by Suzuki et al. was performed. Al3Nb single crystal micron-order size cantilevers with a chevron-notch were fabricated in a grain of two-phase polycrystalline alloys by using FIB (Focused Ion Beam). From the load-displacement curves during the bending by a nanoindenter, the average value of fracture toughness of Nb-rich Al3Nb is evaluated to be 2.90 MPam1/2, while the fracture toughness of Al-rich Al3Nb is also evaluated to be 2.82 MPam1/2. From this result, the fracture toughness of Al3Nb is less dependent on its Al/Nb ratio. Furthermore the fracture toughness of Al3 (Nb, V) was evaluated to be 2.82 MPam1/2.The fracture toughness of Al3Nb is seemingly insensitive to V addition.

Examinations of Oxidation and Sulfidation of Grain Boundaries in Alloy 600 Exposed to Simulated Pressurized Water Reactor Primary Water

2013 ◽  
Vol 19 (3) ◽  
pp. 676-687 ◽  
Author(s):  
D.K. Schreiber ◽  
M.J. Olszta ◽  
D.W. Saxey ◽  
K. Kruska ◽  
K.L. Moore ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Atom Probe Tomography ◽  
Atom Probe ◽  
Alloy 600 ◽  
Pressurized Water Reactor ◽  
Intergranular Attack ◽  
Pressurized Water ◽  
Primary Water

AbstractHigh-resolution characterizations of intergranular attack in alloy 600 (Ni-17Cr-9Fe) exposed to 325°C simulated pressurized water reactor primary water have been conducted using a combination of scanning electron microscopy, NanoSIMS, analytical transmission electron microscopy, and atom probe tomography. The intergranular attack exhibited a two-stage microstructure that consisted of continuous corrosion/oxidation to a depth of ~200 nm from the surface followed by discrete Cr-rich sulfides to a further depth of ~500 nm. The continuous oxidation region contained primarily nanocrystalline MO-structure oxide particles and ended at Ni-rich, Cr-depleted grain boundaries with spaced CrS precipitates. Three-dimensional characterization of the sulfidized region using site-specific atom probe tomography revealed extraordinary grain boundary composition changes, including total depletion of Cr across a several nm wide dealloyed zone as a result of grain boundary migration.

Implementing Transmission Electron Backscatter Diffraction for Atom Probe Tomography

2016 ◽  
Vol 22 (3) ◽  
pp. 583-588 ◽  
Author(s):  
Katherine P. Rice ◽  
Yimeng Chen ◽  
Ty J. Prosa ◽  
David J. Larson
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Atom Probe Tomography ◽  
Focused Ion Beam ◽  
Electron Backscatter Diffraction ◽  
Ion Beam ◽  
Atom Probe ◽  
Specimen Preparation ◽  
Inconel 600 ◽  
Transmission Electron

AbstractThere are advantages to performing transmission electron backscattering diffraction (tEBSD) in conjunction with focused ion beam-based specimen preparation for atom probe tomography (APT). Although tEBSD allows users to identify the position and character of grain boundaries, which can then be combined with APT to provide full chemical and orientation characterization of grain boundaries, tEBSD can also provide imaging information that improves the APT specimen preparation process by insuring proper placement of the targeted grain boundary within an APT specimen. In this report we discuss sample tilt angles, ion beam milling energies, and other considerations to optimize Kikuchi diffraction pattern quality for the APT specimen geometry. Coordinated specimen preparation and analysis of a grain boundary in a Ni-based Inconel 600 alloy is used to illustrate the approach revealing a 50° misorientation and trace element segregation to the grain boundary.

Fabrication of $\bf NdBa_{2}Cu_{3}O_{7-{\ninmbi \delta}}$ (110)-(001) Grain Boundary Josephson Junction by Focused Ion Beam Method

1997 ◽  
Vol 36 (Part 2, No. 6B) ◽  
pp. L764-L766 ◽  
Author(s):  
Yuuji Mizuno ◽  
Yoshihiro Ishimaru ◽  
Jianguo Wen ◽  
Youichi Enomoto
Keyword(s):  
Grain Boundary ◽  
Josephson Junction ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Beam Method

Simulation of the interaction of plastic zone dislocations with the grain boundary at brittle-plastic transition temperatures in molybdenum

2021 ◽  
Vol 2021 (3) ◽  
pp. 77-85
Author(s):  
K. M. Borysovska ◽  
◽  
N. M. Marchenko ◽  
Yu. M. Podrezov ◽  
S. O. Firstov ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Grain Size ◽  
Grain Boundary ◽  
Plastic Zone ◽  
Grain Boundaries ◽  
Crack Tip ◽  
Dynamics Simulation ◽  
Density Of Dislocations ◽  
Grain Sizes ◽  
Pile Up

The (DD) method was used to model the formation of the plastic zone of the top of the cracks in polycrystalline molybdenum. Special attention was paid to take into account the interaction of dislocations in the plastic zone with grain boundaries. Structural sensitivity of fracture toughness was analyzed under brittle-ductile condition. Simulations were performed for a range of grain sizes from 400 to 100 μm, at which a sudden increase in fracture toughness with a decrease of grain size was experimentally shown. We calculated the value of K1c taking into account the shielding action of dislocations. The position of all dislocations in the plastic zone at fracture moment was calculated. Based on these data, we obtained the dependences of dislocation density on the distance from the crack tip thereby confirming significant influence of the grain boundaries on plastic zone formation. At large grain sizes, when the plastic zone does not touch the boundary, the distribution of dislocations remained unchanged. As grains reduce their size to size of the plastic zone, they start formating a dislocation pile – up near the boundaries. Dislocations on plastic zone move slightly toward the crack tip, but the density of dislocations in the middle of the grain remains unchanged, and fracture toughness remains almost unchanged. Further reduction of the grain size leads to the Frank-Reed source activation on the grain boundary Forming dislocation pile-up of the neighbor grains. Its stress concentration acts on dislocations of the first grain and causes redistribution of plastic zone dislocations. If the reduction in grain size is not enough to form a strong pile-up, density of dislocations on plastic zone increases slightly and crack resistance increases a few percent. Further reduction of grains promotes strong pile-up, dislocations move to crack tip, and its density on plastic zone increases. Crack is shielded and fracture toughness increases sharply. The calculation showed that the fracture toughness jump is observed at grain sizes of 100—150 μm, in good agreement with the experiment. Keywords: dislocation dynamics simulation, molybdenum, fracture toughness, grain size, plastic zone, brittle-ductile transition.

scholarly journals Investigation on the Corrosion Behavior of Lean Duplex Stainless Steel 2404 after Aging within the 650–850 °C Temperature Range

Metals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 529 ◽  
Author(s):  
Federica Zanotto ◽  
Vincenzo Grassi ◽  
Andrea Balbo ◽  
Fabrizio Zucchi ◽  
Cecilia Monticelli
Keyword(s):  
Stainless Steel ◽  
Grain Boundaries ◽  
Duplex Stainless Steel ◽  
Corrosion Behavior ◽  
Thermal Aging ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Localized Corrosion ◽  
Fast Diffusion ◽  
Lean Duplex Stainless Steel

This paper reports the effects of thermal aging between 650 and 850 °C on the localized corrosion behavior of lean duplex stainless steel (LDSS 2404). Critical pitting temperature (CPT) and double loop electrochemical potentiokinetic reactivation (DL-EPR) tests were performed. The localization of pitting attack and intergranular corrosion (IGC) attack after DL-EPR was investigated by optical (OM) and scanning electron microscopy (SEM) and by focused ion beam (FIB) coupled to SEM. Thermal aging caused the precipitation of mainly chromium nitrides at grain boundaries. Aging at 650 °C or short aging times (5 min) at 750 °C caused nitride precipitation mainly at α/α grain boundaries as a result of fast diffusion of chromium in this phase. Aging at 850 °C or aging times from 10 to 60 min at 750 °C also allowed the precipitation at the α/γ interface. Nitrides at γ/γ grain boundaries were observed rarely and only after long aging times (60 min) at 850 °C. Electrochemical tests showed that in as-received samples, pitting attack only affected the α phase. Conversely, in aged samples, pitting and IGC attack were detected close to nitrides in correspondence of α/α and α/γ grain boundaries depending on aging temperatures and times.

Assessment of Deformation using the Focused Ion Beam Technique

2000 ◽  
Vol 6 (S2) ◽  
pp. 530-531
Author(s):  
M.G. Burke ◽  
P.T. Duda ◽  
G. Botton ◽  
M. W. Phaneuf
Keyword(s):  
Focused Ion Beam ◽  
Ion Beam ◽  
Site Specificity ◽  
Alloy 600 ◽  
The Past ◽  
Transmission Electron ◽  
Wide Range ◽  
Potential Applications ◽  
Beam Technique ◽  
Significant Attention

Focused Ion Beam (FIB) micromachining techniques have gained significant attention over the past few years as a promising method for the preparation of a variety of metallic and nonmetallic materials for subsequent characterization using transmission electron microscopy (TEM) The advantage of the FIB in terms of site specificity and speed for the preparation of uniform electron transparent sections has opened a wide range of potential applications in materials characterization. The ability to image the sample in the FIB can also provide important microstructural data for materials analysis. In this study, both conventionally electropolished and FIB-ed specimens were prepared in order to characterize the microstructure of a commercially-produced tube of Alloy 600 (approximately Ni-15 Cr-10 Fe- 0.05 C). The electropolished samples were prepared using a solution of 20% HClO4 - 80% CH3OH at ∼-40°C. The FIB sections were obtained from a cross-section of the tube that had been mechanically thinned to ∼100 μm. The section was thinned in a Micrion 2500 FIB system with a Ga ion beam at 50 kV accelerating voltage.

Fracture Toughness of Titanium - Titanium Nitride Multi-Layer Thin Film

2008 ◽  
Author(s):  
Mohan Prasad Manoharan ◽  
Amit Desai ◽  
Amanul Haque
Keyword(s):  
Thin Film ◽  
Fracture Toughness ◽  
Titanium Nitride ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
New Class ◽  
Tin Coatings ◽  
Film Specimen ◽  
Cantilever Bending ◽  
Layer Thin Film

Thin film specimens of titanium - titanium nitride multilayer erosion resistant coating were prepared using liftout technique in Focused Ion Beam - Scanning Electron Microscope (SEM). The fracture toughness of the thin film specimen was measured in situ using a cantilever bending experiment in SEM to be 11.33 MPa/m0.5, twice as much as conventional TiN coatings. Ti–TiN multi-layer coatings are part of a new class of advanced erosion resistant coatings and this paper discusses an experimental technique to measure the fracture toughness of these coatings.

A Membrane Deflection Fracture Experiment to Investigate Fracture Toughness of Freestanding MEMS Materials

2003 ◽  
Vol 795 ◽  
Author(s):  
H. D. Espinosa ◽  
B. Peng
Keyword(s):  
Thin Film ◽  
Fracture Toughness ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Mean Value ◽  
Advanced Materials ◽  
Ultrananocrystalline Diamond ◽  
Membrane Deflection

ABSTRACTThis paper presents a novel Membrane Deflection Fracture Experiment (MDFE) to investigate the fracture toughness of MEMS and other advanced materials in thin film form. It involves the stretching of freestanding thin-film membranes, in a fixed-fixed configuration, containing pre-existing cracks. The fracture behavior of ultrananocrystalline diamond (UNCD), a material developed at Argonne National Laboratory, is investigated to illustrate the methodology. When the fracture initiates from sharp cracks, produced by indentation, the fracture toughness was found to be 4.7 MPa m1/2. When the fracture initiates from blunt notches with radii about 100 nm, machined by focused ion beam (FIB), the mean value of the apparent fracture toughness was found to be 7.2 MPa m1/2. Comparison of these two values, using the model proposed by Drory et al. [9], provides a correction factor of 2/3, which corresponds to a mean value of ρ/2x=1/2.

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