AN ATOM-PROBE STUDY OF Fe-Ti ALLOYS

1984 ◽  
Vol 45 (C9) ◽  
pp. C9-417-C9-422
Author(s):  
A. Jimbo ◽  
T. Hashizume ◽  
T. Sakurai ◽  
K. Al-Saleh ◽  
H. W. Pickering
Keyword(s):  
Atom Probe ◽  
Ti Alloys

scholarly journals Atom Probe Tomographic Studies of Precipitation in Al-0.1Zr-0.1Ti (at.%) Alloys

2007 ◽  
Vol 13 (6) ◽  
pp. 503-516 ◽  
Author(s):  
Keith E. Knipling ◽  
David C. Dunand ◽  
David N. Seidman
Keyword(s):  
Atom Probe Tomography ◽  
Local Thermodynamic Equilibrium ◽  
Atom Probe ◽  
Atomic Ratio ◽  
Chemical Compositions ◽  
Ti Alloys ◽  
The Matrix ◽  
Solute Atoms ◽  
Interfacial Segregation ◽  
Zr Alloys

Atom probe tomography was utilized to measure directly the chemical compositions of Al3(Zr1−xTix) precipitates with a metastable L12 structure formed in Al-0.1Zr-0.1Ti (at.%) alloys upon aging at 375°C or 425°C. The alloys exhibit an inhomogeneous distribution of Al3(Zr1−xTix) precipitates, as a result of a nonuniform dendritic distribution of solute atoms after casting. At these aging temperatures, the Zr:Ti atomic ratio in the precipitates is about 10 and 5, respectively, indicating that Ti remains mainly in solid solution rather than partitioning to the Al3(Zr1−xTix) precipitates. This is interpreted as being due to the very small diffusivity of Ti in α-Al, consistent with prior studies on Al-Sc-Ti and Al-Sc-Zr alloys, where the slower diffusing Zr and Ti atoms make up a small fraction of the Al3(Sc1−xTix/Zrx) precipitates. Unlike those alloys, however, the present Al-Zr-Ti alloys exhibit no interfacial segregation of Ti at the matrix/precipitate heterophase interface, a result that may be affected by a significant disparity in the evaporation fields of the α-Al matrix and Al3(Zr1−xTix) precipitates and/or a lack of local thermodynamic equilibrium at the interface.

Interplay between eutectic and dendritic growths dominated by Si content for Nb-Si-Ti alloys via rapid solidification

2021 ◽  
pp. 1-20
Author(s):  
Yueling Guo ◽  
Lina Jia ◽  
Junyang He ◽  
Siyuan Zhang ◽  
Zhiming Li ◽  
...  
Keyword(s):  
Electron Beam ◽  
Rapid Solidification ◽  
Atom Probe ◽  
Ti Alloys ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Beam Surface ◽  
Si Content ◽  
Design And Manufacture ◽  
Fully Lamellar

Abstract Rapid solidification techniques such as electron beam additive manufacturing are considered as promising pathways for manufacturing Nb-Si based alloys for ultra-high-temperature applications. Here we investigate the microstructure diversity of a series of Nb-Si-Ti alloys via electron beam surface melting (EBSM) to reveal their rapid solidification behaviors. Results show that the microstructural transition from coupled to divorced Nbss/Nb3Si eutectics can be triggered by increasing Si content. The formation of fully lamellar eutectics, evidenced by scanning transmission electron microscopy and atom probe tomography (APT), is achieved in the EBSM-processed Nb18Si20Ti alloy (at%), in contrast to the hypereutectic microstructures in arc-melted counterparts. The dendritic microstructures containing divorced eutectics are generated with a higher content of Si during rapid solidification. The transition from faceted to non-faceted growth of intermetallic Nb3Si occurs with the formation of primary Nb3Si dendrites. The interplay between eutectic and dendritic growths of silicides is discussed to provide insights for future alloy design and manufacture.

scholarly journals Influence of Composition and Structure on Measured H Concentration in beta-Ti Alloys via Atom Probe Tomography

2019 ◽  
Vol 25 (S2) ◽  
pp. 2542-2543
Author(s):  
JoAnn Ballor ◽  
Elizabeth Kautz ◽  
Bharat Gwalani ◽  
Carl Boehlert ◽  
Arun Devaraj
Keyword(s):  
Atom Probe Tomography ◽  
Atom Probe ◽  
Ti Alloys ◽  
Composition And Structure

scholarly journals Correlation between Microstructural Change and Irradiation Hardening Behavior of He-Irradiated V–Cr–Ti Alloys with Low Ti Addition

2021 ◽  
Vol 5 (3) ◽  
pp. 26
Author(s):  
Ken-ichi Fukumoto ◽  
Shuichiro Miura ◽  
Yoshiki Kitamura ◽  
Ryoya Ishigami ◽  
Takuya Nagasaka
Keyword(s):  
Microstructural Evolution ◽  
Atom Probe ◽  
Vanadium Alloys ◽  
Irradiation Hardening ◽  
Fusion Neutron ◽  
Hardening Behavior ◽  
Ti Alloys ◽  
Transmission Electron ◽  
Hardening Theory ◽  
Ti Addition

V–4Cr–xTi (x = 0 to 4) alloys were used to investigate the additional effect of Cr, Ti and interstitial impurities on the microstructural evolution in He-irradiated V–Cr–Ti alloys to minimize radioactivity after fusion neutron irradiation. Transmission electron microscopy and atom probe tomography were carried out to the He-irradiated specimens at 500 °C with 0.5 dpa at peak damage. A flash electro-polishing method for the FIB-extracted specimen was established for the ion-irradiated vanadium alloys. The microstructural evolution of the irradiation-induced titanium-oxycarbonitride, Ti(CON) precipitates was observed and was influenced by the effect of Ti addition on the Ti(CON) precipitation. Apparent Ti(CON) precipitates formed in V-4Cr-xTi with 2% addition of Ti. In the V-4Cr-1Ti alloy, a high density Ti enriched cluster was formed. The origin of the irradiation hardening increase resulted from the size distribution of Ti(CON) precipitation from the dispersed barrier-hardening theory.

Precipitation Kinetics Study of Al – Zr – X(Sc or Ti) Alloys by Phase Field Simulations and Atom Probe Tomography

2011 ◽  
Vol 172-174 ◽  
pp. 869-874
Author(s):  
Nicolas Masquelier ◽  
Helena Zapolsky ◽  
Williams Lefebvre ◽  
Suzana Gomes Fries ◽  
Renaud Patte ◽  
...  
Keyword(s):  
Phase Field ◽  
Atom Probe ◽  
Ternary Alloys ◽  
Kinetics Study ◽  
Matrix Interface ◽  
Precipitation Kinetics ◽  
Phase Field Modeling ◽  
Ti Alloys ◽  
Field Modeling ◽  
Simulation Results

Phase field modeling of precipitation kinetics in Al – Zr – Sc and Al – Zr – Ti ternary alloys has been performed. The free energy was evaluated using the Thermo-calc data. Our simulations showed that L12precipitates in Al – Zr – Sc alloy consists of Sc rich zone of in core and Zirconium rich zone at the precipitate / matrix interface. In Al – Zr – Ti system, Al3(Zr-Ti) precipitates are homogeneous and no segregation is observed. Phase-field simulation results are compared with 3D APT data.

Direct Observation of the Diffusionless β → β + ω Transformation in Titanium Alloys

1971 ◽  
Vol 29 ◽  
pp. 122-123
Author(s):  
N. E. Paton ◽  
D. de Fontaine ◽  
J. C. Williams
Keyword(s):  
Electron Microscope ◽  
Titanium Alloys ◽  
Direct Observation ◽  
Dark Field ◽  
X Ray Diffraction ◽  
Resistivity Measurements ◽  
Selected Area Electron Diffraction ◽  
Ti Alloys ◽  
Thin Foils ◽  
Field Device

The electron microscope has been used to study the diffusionless β → β + ω transformation occurring in certain titanium alloys at low temperatures. Evidence for such a transformation was obtained by Cometto et al by means of x-ray diffraction and resistivity measurements on a Ti-Nb alloy. The present work shows that this type of transformation can occur in several Ti alloys of suitable composition, and some of the details of the transformation are elucidated by means of direct observation in the electron microscope.Thin foils were examined in a Philips EM-300 electron microscope equipped with a uniaxial tilt, liquid nitrogen cooled, cold stage and a high resolution dark field device. Selected area electron diffraction was used to identify the phases present and the ω-phase was imaged in dark field by using a (101)ω reflection. Alloys were water quenched from 950°C, thinned, and mounted between copper grids to minimize temperature gradients in the foil.

Preferential Sputtering of Ni3Al Single Crystals Studied Using Atom-Probe Field-Ion Microscopy and XPS

1981 ◽  
Vol 39 ◽  
pp. 16-17
Author(s):  
M.P. Thomas ◽  
A.R. Waugh ◽  
M.J. Southon ◽  
Brian Ralph
Keyword(s):  
Single Crystals ◽  
Photoelectron Spectroscopy ◽  
Surface Composition ◽  
Depth Profiling ◽  
Analytical Techniques ◽  
Atom Probe ◽  
Probe Field ◽  
Preferential Sputtering ◽  
Argon Ion Bombardment ◽  
Argon Ion

It is well known that ion-induced sputtering from numerous multicomponent targets results in marked changes in surface composition (1). Preferential removal of one component results in surface enrichment in the less easily removed species. In this investigation, a time-of-flight atom-probe field-ion microscope A.P. together with X-ray photoelectron spectroscopy XPS have been used to monitor alterations in surface composition of Ni3Al single crystals under argon ion bombardment. The A.P. has been chosen for this investigation because of its ability using field evaporation to depth profile through a sputtered surface without the need for further ion sputtering. Incident ion energy and ion dose have been selected to reflect conditions widely used in surface analytical techniques for cleaning and depth-profiling of samples, typically 3keV and 1018 - 1020 ion m-2.

High-resolution x-ray imaging of small copper-rich precipitates in steels

1988 ◽  
Vol 46 ◽  
pp. 528-529
Author(s):  
J. R. Michael ◽  
K. A. Taylor
Keyword(s):  
Electron Microscopy ◽  
Thermomechanical Processing ◽  
Atom Probe ◽  
Ferrite Matrix ◽  
Scanning Transmission Electron Microscope ◽  
Probe Field ◽  
X Ray ◽  
Subsequent Transformation ◽  
Transmission Electron ◽  
Scanning Transmission

Although copper is considered an incidental or trace element in many commercial steels, some grades contain up to 1-2 wt.% Cu for precipitation strengthening. Previous electron microscopy and atom-probe/field-ion microscopy (AP/FIM) studies indicate that the precipitation of copper from ferrite proceeds with the formation of Cu-rich bcc zones and the subsequent transformation of these zones to fcc copper particles. However, the similarity between the atomic scattering amplitudes for iron and copper and the small misfit between between Cu-rich particles and the ferrite matrix preclude the detection of small (<5 nm) Cu-rich particles by conventional transmission electron microscopy; such particles have been imaged directly only by FIM. Here results are presented whereby the Cu Kα x-ray signal was used in a dedicated scanning transmission electron microscope (STEM) to image small Cu-rich particles in a steel. The capability to detect these small particles is expected to be helpful in understanding the behavior of copper in steels during thermomechanical processing and heat treatment.

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