Transmission electron microscope and transmission electron diffraction observations of alloy clustering in liquid‐phase epitaxial (001) GaInAsP layers

1985 ◽  
Vol 57 (10) ◽  
pp. 4715-4720 ◽  
Author(s):  
A. G. Norman ◽  
G. R. Booker
Keyword(s):  
Electron Microscope ◽  
Liquid Phase ◽  
Electron Diffraction ◽  
Transmission Electron Microscope ◽  
Transmission Electron Diffraction ◽  
Liquid Phase Epitaxial ◽  
Transmission Electron

Host Phases for Actinide Elements in the Metallic Waste Form

2002 ◽  
Vol 757 ◽  
Author(s):  
D. E. Janney
Keyword(s):  
Stainless Steel ◽  
Electron Microscope ◽  
Electron Diffraction ◽  
Transmission Electron Microscope ◽  
Waste Form ◽  
Dissolution Behavior ◽  
Release Rates ◽  
Waste Forms ◽  
Transmission Electron ◽  
Simulated Waste

ABSTRACTArgonne National Laboratory has developed an electrometallurgical process for conditioning spent sodium-bonded metallic reactor fuel prior to disposal. A waste stream from this process consists of stainless steel cladding hulls that contain undissolved metal fission products such as Tc, Ru, Rh, Pd, and Ag; a small amount of undissolved actinides (U, Np, Pu) also remains with the hulls. These wastes will be immobilized in a waste form whose baseline composition is stainless steel alloyed with 15 wt% Zr (SS-15Zr). Scanning electron microscope (SEM) observations of simulated metal waste forms (SS-15Zr with up to 11 wt% actinides) show eutectic intergrowths of Fe-Zr-Cr-Ni intermetallic phases with steels. The actinide elements are almost entirely in the intermetallics, where they occur in concentrations ranging from 1–20 at%. Neutron- and electron-diffraction studies of the simulated waste forms show materials with structures similar to those of Fe2Zr and Fe23Zr6.Dissolution experiments on simulated waste forms show that normalized release rates of U, Np, and Pu differ from each other and from release rates of other elements in the sample, and that release rates for U exceed those for any other element (including Fe). This paper uses transmission electron microscope (TEM) observations and results from energy-dispersive X-ray spectroscopy (EDX) and selected-area electron-diffraction (SAED) to characterize relationships between structural and chemical data and understand possible reasons for the observed dissolution behavior.Transmission electron microscope observations of simulated waste form samples with compositions SS-15Zr-2Np, SS-15Zr-5U, SS-15Zr-11U-0.6Rh-0.3Tc-0.2Pd, and SS-15Zr-10Pu suggest that the major actinide-bearing phase in all of the samples has a structure similar to that of the C15 (cubic, MgCu2-type) polymorph of Fe2Zr, and that materials with this structure exhibit significant variability in chemical compositions. Material whose structure is similar to that of the C36 (dihexagonal, MgNi2-type) polymorph of Fe2Zr was also observed, and it exhibits less chemical variability than that displayed by material with the C15 structure. The TEM data also demonstrate a range of actinide concentrations in materials with the Fe23Zr6 (cubic, Mn23Th6-type) structure.Microstructures similar to those produced during experimental deformation of Fe-10 at% Zr alloys were observed in intermetallic materials in all of the simulated waste form samples. Stacking faults and associated dislocations are common in samples with U, but rarely observed in those with Np and Pu, while twins occurred in all samples. The observed differences in dissolution behavior between samples with different actinides may be related to increased defect-assisted dissolution in samples with U.

In situ electron diffraction study of synthetic (Ca1-xSrx)2MgSi2O7 åkermanites

2000 ◽  
Vol 215 (9) ◽  
Author(s):  
H. Rager ◽  
M. Schosnig ◽  
A.K. Schaper ◽  
A. Kutoglu ◽  
W. Treutmann
Keyword(s):  
Phase Transitions ◽  
Electron Microscope ◽  
Electron Diffraction ◽  
Diffraction Study ◽  
Solid Solutions ◽  
Transmission Electron Microscope ◽  
Electron Diffraction Study ◽  
Modulated Structure ◽  
Transmission Electron

This paper deals with transmission electron microscope experiments of Ca,Sr-åkermanite solid solutions at temperatures between 100 K and 375 K. The aim of the investigations was to study the compositional and temperature dependence of phase transitions from the normal to the incommensurately modulated structure of(Ca

In Situ Transmission Electron Microscope Observation of Melting of Aluminum Particles

1998 ◽  
Vol 4 (3) ◽  
pp. 264-268 ◽  
Author(s):  
S. Arai ◽  
S. Tsukimoto ◽  
H. Saka
Keyword(s):  
Electron Microscope ◽  
Liquid Phase ◽  
Transmission Electron Microscope ◽  
Microscope Observation ◽  
Crystalline Solid ◽  
Electron Microscope Observation ◽  
Aluminum Particles ◽  
Transmission Electron Microscope Observation ◽  
Transmission Electron

The processes of melting and freezing of aluminum (Al) particles have been observed directly in a transmission electron microscope. The liquid phase nucleated preferentially at the surface of an Al particle, surrounding the crystalline solid at the onset of melting. The liquid phase then propagated inside the Al particle at the expense of the solid.

Structure Transformations of the Decagonal and Icosahedral Phases in Quaternary Alloys.

1991 ◽  
Vol 235 ◽  
Author(s):  
R. Perez ◽  
J. Reyes-Gasga ◽  
M. Jose-Yacaman
Keyword(s):  
Electron Microscope ◽  
Electron Diffraction ◽  
Transmission Electron Microscope ◽  
Icosahedral Phase ◽  
Electron Radiation ◽  
Quaternary Alloys ◽  
Decagonal Phase ◽  
Icosahedral Phases ◽  
Transmission Electron ◽  
Diffraction Patterns

ABSTRACTAn investigation of the phase transformations experienced by the decagonal and icosahedral phases in two different quaternary -alloys is carried out. The transformation in the decagonal phase of Al-Cu-Co-Si alloy is induced by the electron radiation in a transmission electron microscope. However, in the icosahedral phase of Al-Cu-Co-Fe alloy this transformation is induced by annealing. Electron diffraction patterns obtained from both phases suggest that the deformation mechanism involved in these kind of transitions is related with twinning

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