Chemical and Structural Characterization of γ/γ′ Interfaces

2012 ◽  
Vol 463-464 ◽  
pp. 20-24
Author(s):  
Kai Zhao
Keyword(s):  
Atom Probe Tomography ◽  
Three Dimensional ◽  
Atom Probe ◽  
Scanning Transmission Electron Microscope ◽  
Atomic Scale ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Nickel Base

More attention has been paid to the interfaces since mechanical properties of nickel-base superalloys are determined to some degree by them. The compositional transition across γ/γ′ interfaces and atomic structure of the interfaces was investigated using three-dimensional atom probe tomography and scanning transmission electron microscope equipped with high-resolution Energy Dispersive X-ray Spectrometry. Results show that no obvious segregation to the interfaces or ledges of the precipitates in the present experimental alloys has been observed. Also, adsorption of a solute to the interface was not observed. The interfaces are not flat as usually thought at an atomic scale. The interfacial thickness is about two atomic layers, i.e. 0.7 nm.

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.

scholarly journals Atom-probe Tomography, Small Angle Neutron Scattering, Transmission Electron Microscopy, Positron Annihilation Spectroscopy and X-ray Absorption Spectroscopy Characterization of Nano-scale Features in Nanostructured Ferritic Alloys

2009 ◽  
Vol 15 (S2) ◽  
pp. 244-245 ◽  
Author(s):  
GR Odette ◽  
NJ Cunningham ◽  
EA Marquis ◽  
S Lozano-Perez ◽  
V de Castro ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Atom Probe Tomography ◽  
Small Angle Neutron Scattering ◽  
Positron Annihilation Spectroscopy ◽  
Atom Probe ◽  
Ferritic Alloys ◽  
X Ray ◽  
Transmission Electron ◽  
X Ray Absorption

Extended abstract of a paper presented at Microscopy and Microanalysis 2009 in Richmond, Virginia, USA, July 26 – July 30, 2009

Atomic Scale Structural Characterization of Epitaxial (Cd,Cr)Te Magnetic Semiconductor

2017 ◽  
Vol 23 (4) ◽  
pp. 717-723 ◽  
Author(s):  
Bastien Bonef ◽  
Hervé Boukari ◽  
Adeline Grenier ◽  
Isabelle Mouton ◽  
Pierre-Henri Jouneau ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Magnetic Semiconductors ◽  
Magnetic Semiconductor ◽  
Atom Probe ◽  
Scanning Transmission Electron Microscope ◽  
Atomic Scale ◽  
Detailed Knowledge ◽  
Inhomogeneous Materials ◽  
Transmission Electron ◽  
Scanning Transmission

AbstractA detailed knowledge of the atomic structure of magnetic semiconductors is crucial to understanding their electronic and magnetic properties, which could enable spintronic applications. Energy-dispersive X-ray spectrometry (EDX) in the scanning transmission electron microscope and atom probe tomography (APT) experiments reveal the formation of Cr-rich regions in Cd1−xCrxTe layers grown by molecular beam epitaxy. These Cr-rich regions occur on a length scale of 6–10 nm at a nominal Cr composition of x=0.034 and evolve toward an ellipsoidal shape oriented along <111> directions at a composition of x=0.083. Statistical analysis of the APT reconstructed volume reveals that the Cr aggregation increases with the average Cr composition. The correlation with the magnetic properties of such (Cd,Cr)Te layers is discussed within the framework of strongly inhomogeneous materials. Finally, difficulties in accurately quantifying the Cr distribution in the CdTe matrix on an atomic scale by EDX and APT are discussed.

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