The study of texture and grain boundary misorientation in multiphase materials has been greatly b... more The study of texture and grain boundary misorientation in multiphase materials has been greatly benefited from the recent automation of the electron back-scattered diffraction (EBSD) technique. With this technique, each phase in a multiphase material can be individually sampled and analyzed. This is of great significance and interest in the study of thin films, inclusions and multiphase alloys. Spatial resolution, which depends on experimental conditions such as beam energy and specimen tilt, and the material being studied, is critical in order to determine the orientation of different phases in multiphase materials.The Monte Carlo (MC) method has been effectively used to investigate spatial resolution in single phase materials. In this paper, the MC simulation is modified and applied to two-phase geometries. For a bulk two phase (Al/Au) specimen, the coordinate system was defined such that the x-axis was normal to the electron beam and the interface, y-axis parallel to the interfac...
Proceedings, annual meeting, Electron Microscopy Society of America
The radiation response of metallic alloys can be strongly dependent on specific solute elements. ... more The radiation response of metallic alloys can be strongly dependent on specific solute elements. Void swelling and phase instability of the matrix are two primary concerns in the design of nuclear reactors. A 316 stainless steel, LS1A, with greater than nominal levels of silicon and titanium has been developed which exhibits high resistance to swelling under ion irradiation. The origin of this swelling resistance and the roles of silicon and titanium have been investigated in the current study.Figure 1 illustrates the evolution of the damage structure in LS1A under nickel ion irradiation at 625°C. At low dose [∽1 dpa, Fig. 1(a)], faulted interstitial dislocation loops (43-nm-av diam) are observed. We have previously reported that significant solute silicon segregation (approaching 7.0 at. %) in the vicinity of the loop fault plane occurs at such doses in LS1A. Below 10 dpa, precipitates appear to replace the loops in similar sizes and densities. At 70 dpa [Fig. 1(b)] there is no swe...
Proceedings, annual meeting, Electron Microscopy Society of America
The 100 meter Long Drop Tube, located within the Marshall Space Flight Center in Huntsville, AL, ... more The 100 meter Long Drop Tube, located within the Marshall Space Flight Center in Huntsville, AL, provides a unique opportunity for the study of rapid solidification of bulk processed materials. Here, Nb-Ge alloys have been melted into large drops in an electromagnetic levitation furnace, and then released to fall down the tube. Drops were approximately 300 mg in mass and 2-3 mm in diameter. A data acquisition system recorded the release temperature, and the resulting cooling curve from each specimen which may have included recalescence events. Knowledge of thermophysical parameters then allowed the determination of the undercooling. More extensive discussions of the drop tube are elsewhere. Undercoolings of 350 K (0.15 Tm) have been achieved.
Proceedings, annual meeting, Electron Microscopy Society of America
The Shared Research Equipment (SHaRE) Program provides access to the wide range of advanced equip... more The Shared Research Equipment (SHaRE) Program provides access to the wide range of advanced equipment and techniques available in the Metals and Ceramics Division of ORNL to researchers from universities, industry, and other national laboratories. All SHaRE projects are collaborative in nature and address materials science problems in areas of mutual interest to the internal and external collaborators. While all facilities in the Metals and Ceramics Division are available under SHaRE, there is a strong emphasis on analytical electron microscopy (AEM), based on state-of-the-art facilities, techniques, and recognized expertise in the Division. The microscopy facilities include four analytical electron microscopes (one 300 kV, one 200 kV, and two 120 kV instruments), a conventional transmission electron microscope with a low field polepiece for examination of ferromagnetic materials, a high voltage (1 MV) electron microscope with a number of in situ capabilities, and a variety of EM su...
Proceedings, annual meeting, Electron Microscopy Society of America
Radiation-induced segregation (RIS) is driven by fluxes of point defects to sinks. RIS can induce... more Radiation-induced segregation (RIS) is driven by fluxes of point defects to sinks. RIS can induce composition fluctuations in irradiated stainless steels, which can result in microstructural and property changes, including precipitation, austenite instability, strengthening, embrittlement, and irradiation-assisted sensitization and stress corrosion cracking. Analytical electron microscopy (AEM) provides a powerful technique to study such segregation. RIS in several irradiated stainless steels has been investigated. AEM was performed in a Philips EM400T/FEG equipped with an EDAX 9100/70 analysis system. The specimens were neutron irradiated to 15 displacements per atom (dpa) at 520 ° C in the Fast Flux Test Facility (FFTF) and were only mildly radioactive (<50/μCi = 1.85 MBq), thus permitting high spatial resolution X-ray microanalysis to be employed. Typical acquisitions were performed for 100 s in the STEM mode with <2-nm-diam probes containing >0.5 nA current. Subtraction...
Proceedings, annual meeting, Electron Microscopy Society of America
Duplex (austenite/ferrite) stainless steels are used in a variety of applications in the nuclear ... more Duplex (austenite/ferrite) stainless steels are used in a variety of applications in the nuclear industry, particularly for coolant pipes, valves and pumps. These materials may become embrittled after prolonged ageing in the temperature range ∼350 - 550°C due to precipitation of G-phase, an FCC-based Ni silicide, and the formation of a Cr-rich α' phase in the ferrite. In addition to the intragranular G-phase precipitates, preferential precipitation of other phases is often observed at grain boundaries, particularly α/γ interfaces. In this examination, the precipitates formed in a Nb-containing duplex stainless steel have been identified using analytical electron microscopy.
Proceedings, annual meeting, Electron Microscopy Society of America
Segregation of solute atoms to grain boundaries, dislocations, and other extended defects can occ... more Segregation of solute atoms to grain boundaries, dislocations, and other extended defects can occur under thermal equilibrium or non-equilibrium conditions, such as quenching, irradiation, or precipitation. Generally, equilibrium segregation is narrow (near monolayer coverage at planar defects), whereas non-equilibrium segregation exhibits profiles of larger spatial extent, associated with diffusion of point defects or solute atoms. Analytical electron microscopy provides tools both to measure the segregation and to characterize the defect at which the segregation occurs. This is especially true of instruments that can achieve fine (<2 nm width), high current probes and as such, provide high spatial resolution analysis and characterization capability. Analysis was performed in a Philips EM400T/FEG operated in the scanning transmission mode with a probe diameter of <2 nm (FWTM). The instrument is equipped with EDAX 9100/70 energy dispersive X-ray spectrometry (EDXS) and Gatan 6...
Proceedings, annual meeting, Electron Microscopy Society of America
The technological development of aluminum nitride (A1N) substrates is driven to a large extent to... more The technological development of aluminum nitride (A1N) substrates is driven to a large extent towards the economical production of high thermal conductivity sintered ceramics for substrate applications. Stringent demands on matrix purity combined with the practical necessity of sintering additives have led to extensive analyses of property controlling matrix defect structures and of the role of additives in both matrix purification and sintering. Of particular interest are defects such as inversion domain boundaries (IDBs) and grain boundaries which may serve as segregation sites for the dominant impurities in A1N, particularly oxygen. In this work quantitative methods of analytical electron microscopy are applied to the analysis of chemical segregation in electronic grade A1N.Energy dispersive x-ray spectroscopy (EDAX 9100) using a ∼2-nm-diam. probe (Philips EM400T/FEG) has revealed the segregation of yttrium and calcium to the grain boundaries of commercial Toshiba N-170 ceramics...
Proceedings, annual meeting, Electron Microscopy Society of America
Radiation-induced segregation (RIS) and associated irradiation-assisted stress corrosion cracking... more Radiation-induced segregation (RIS) and associated irradiation-assisted stress corrosion cracking (IASCC) of austenitic alloys may be a major factor in limiting component lifetimes in water-cooled nuclear reactors. There are some similarities between radiation-induced sensitization/IASCC and thermally-induced sensitization/intergranular stress corrosion cracking. Both processes are associated with chromium depletion at grain boundaries. Segregation to boundaries in a neutron irradiated type 316 stainless steel has been investigated with both energy-dispersive X-ray spectrometry (EDXS) and parallel detection electron energy loss spectrometry (PEELS).All specimens were from the same heat of cold-worked type 316 stainless steel. Both unirradiated control material and material irradiated at ∼300°C to a range of fluences 0.3 - 5 × 1026 neutrons/m2 (E>0.1 MeV) were available. The mass of irradiated material was minimized by mechanically polishing 3-mm-diam. disks to ∼75 μm thickness pr...
The Shared Research Equipment (SHaRE) User Facility and Program at Oak Ridge National Laboratory ... more The Shared Research Equipment (SHaRE) User Facility and Program at Oak Ridge National Laboratory (ORNL) provides microanalytical facilities for studies within the materials sciences. Available instrumentation includes advanced analytical electron microscopes, atom probe field ion microscopes, and nanoindentation facilities. Through SHaRE, researchers from U.S. universities, industries, and government laboratories may collaborate with Facility scientists to perform research not possible at their home institutions. International collaborations are also possible. Most SHaRE projects seek correlations at the microscopic or atomic scale between structure and properties in a wide range of metallic, ceramic, and other structural materials. Typical research projects include studies of magnetic materials, advanced alloys, catalysts, semiconductor device materials, high Tc superconductors, and surface-modified polymers. Projects usually involve one or more external researchers visiting the SH...
Whereas the spatial resolution for standard secondary electron (SEI) imaging in a scanning electr... more Whereas the spatial resolution for standard secondary electron (SEI) imaging in a scanning electron microscope or electron probe microanalyzer is related to the incident probe diameter, the spatial resolution for x-ray microanalysis is related to the convolution of the probe diameter with the spatial extent of the analyzed volume for a point probe. The latter is determined by electron scattering in the specimen and the subsequent emission of excited x-rays from the specimen. As such, it is possible that “What you see is not what you get”. This is especially true for instruments with high brightness electron sources (field emission). This problem is compounded by probe aberrations which at Gaussian image focus can produce significant electron tails extending tens of microns from the center of the probe.
Experiments and simulations show that the microstructural stability of nanocrystalline Cu can be ... more Experiments and simulations show that the microstructural stability of nanocrystalline Cu can be improved by adding impurity atoms, such as Sb, which migrate to the grain boundaries. Cu100-xSbx alloys are cast in three compositions (Cu-0.0, 0.2 and 0.5 at.%Sb) and subsequently processed into nanocrystalline form by equal channel angular extrusion (ECAE). The presence of Sb atoms at the grain boundaries
ABSTRACTTitanium nitride crystals were grown from titanium nitride powder on tungsten by the subl... more ABSTRACTTitanium nitride crystals were grown from titanium nitride powder on tungsten by the sublimation-recondensation technique. The bright golden TiN crystals displayed a variety of shapes including cubes, truncated tetrahedrons, truncated octahedrons, and tetrahedrons bounded by (111) and (100) crystal planes. The TiN crystals formed regular, repeated patterns within individual W grains that suggested epitaxy. X-ray diffraction and electron backscattering diffraction revealed that the tungsten foil was highly textured with a preferred foil normal of (100) and confirmed that the TiN particles deposited epitaxially with the orientation TiN(100)‖W(100) and TiN[100]‖W[110], that is, the unit cells of the TiN crystals were rotated 45° with respect to the tungsten. Because of its larger coefficient of thermal expansion compared to W, upon cooling from the growth temperature, the TiN crystals were under in-plane tensile strain, causing many of the TiN crystals to crack.
Multiple-walled carbon nanotubes (MWNTs) produced using the chemical vapor deposition method were... more Multiple-walled carbon nanotubes (MWNTs) produced using the chemical vapor deposition method were functionalized via attaching aminopolymer poly(propionylethylenimine-co-ethylenimine ) to the nanotubes. Two different reaction conditions based on acylating the ...
The study of texture and grain boundary misorientation in multiphase materials has been greatly b... more The study of texture and grain boundary misorientation in multiphase materials has been greatly benefited from the recent automation of the electron back-scattered diffraction (EBSD) technique. With this technique, each phase in a multiphase material can be individually sampled and analyzed. This is of great significance and interest in the study of thin films, inclusions and multiphase alloys. Spatial resolution, which depends on experimental conditions such as beam energy and specimen tilt, and the material being studied, is critical in order to determine the orientation of different phases in multiphase materials.The Monte Carlo (MC) method has been effectively used to investigate spatial resolution in single phase materials. In this paper, the MC simulation is modified and applied to two-phase geometries. For a bulk two phase (Al/Au) specimen, the coordinate system was defined such that the x-axis was normal to the electron beam and the interface, y-axis parallel to the interfac...
Proceedings, annual meeting, Electron Microscopy Society of America
The radiation response of metallic alloys can be strongly dependent on specific solute elements. ... more The radiation response of metallic alloys can be strongly dependent on specific solute elements. Void swelling and phase instability of the matrix are two primary concerns in the design of nuclear reactors. A 316 stainless steel, LS1A, with greater than nominal levels of silicon and titanium has been developed which exhibits high resistance to swelling under ion irradiation. The origin of this swelling resistance and the roles of silicon and titanium have been investigated in the current study.Figure 1 illustrates the evolution of the damage structure in LS1A under nickel ion irradiation at 625°C. At low dose [∽1 dpa, Fig. 1(a)], faulted interstitial dislocation loops (43-nm-av diam) are observed. We have previously reported that significant solute silicon segregation (approaching 7.0 at. %) in the vicinity of the loop fault plane occurs at such doses in LS1A. Below 10 dpa, precipitates appear to replace the loops in similar sizes and densities. At 70 dpa [Fig. 1(b)] there is no swe...
Proceedings, annual meeting, Electron Microscopy Society of America
The 100 meter Long Drop Tube, located within the Marshall Space Flight Center in Huntsville, AL, ... more The 100 meter Long Drop Tube, located within the Marshall Space Flight Center in Huntsville, AL, provides a unique opportunity for the study of rapid solidification of bulk processed materials. Here, Nb-Ge alloys have been melted into large drops in an electromagnetic levitation furnace, and then released to fall down the tube. Drops were approximately 300 mg in mass and 2-3 mm in diameter. A data acquisition system recorded the release temperature, and the resulting cooling curve from each specimen which may have included recalescence events. Knowledge of thermophysical parameters then allowed the determination of the undercooling. More extensive discussions of the drop tube are elsewhere. Undercoolings of 350 K (0.15 Tm) have been achieved.
Proceedings, annual meeting, Electron Microscopy Society of America
The Shared Research Equipment (SHaRE) Program provides access to the wide range of advanced equip... more The Shared Research Equipment (SHaRE) Program provides access to the wide range of advanced equipment and techniques available in the Metals and Ceramics Division of ORNL to researchers from universities, industry, and other national laboratories. All SHaRE projects are collaborative in nature and address materials science problems in areas of mutual interest to the internal and external collaborators. While all facilities in the Metals and Ceramics Division are available under SHaRE, there is a strong emphasis on analytical electron microscopy (AEM), based on state-of-the-art facilities, techniques, and recognized expertise in the Division. The microscopy facilities include four analytical electron microscopes (one 300 kV, one 200 kV, and two 120 kV instruments), a conventional transmission electron microscope with a low field polepiece for examination of ferromagnetic materials, a high voltage (1 MV) electron microscope with a number of in situ capabilities, and a variety of EM su...
Proceedings, annual meeting, Electron Microscopy Society of America
Radiation-induced segregation (RIS) is driven by fluxes of point defects to sinks. RIS can induce... more Radiation-induced segregation (RIS) is driven by fluxes of point defects to sinks. RIS can induce composition fluctuations in irradiated stainless steels, which can result in microstructural and property changes, including precipitation, austenite instability, strengthening, embrittlement, and irradiation-assisted sensitization and stress corrosion cracking. Analytical electron microscopy (AEM) provides a powerful technique to study such segregation. RIS in several irradiated stainless steels has been investigated. AEM was performed in a Philips EM400T/FEG equipped with an EDAX 9100/70 analysis system. The specimens were neutron irradiated to 15 displacements per atom (dpa) at 520 ° C in the Fast Flux Test Facility (FFTF) and were only mildly radioactive (<50/μCi = 1.85 MBq), thus permitting high spatial resolution X-ray microanalysis to be employed. Typical acquisitions were performed for 100 s in the STEM mode with <2-nm-diam probes containing >0.5 nA current. Subtraction...
Proceedings, annual meeting, Electron Microscopy Society of America
Duplex (austenite/ferrite) stainless steels are used in a variety of applications in the nuclear ... more Duplex (austenite/ferrite) stainless steels are used in a variety of applications in the nuclear industry, particularly for coolant pipes, valves and pumps. These materials may become embrittled after prolonged ageing in the temperature range ∼350 - 550°C due to precipitation of G-phase, an FCC-based Ni silicide, and the formation of a Cr-rich α' phase in the ferrite. In addition to the intragranular G-phase precipitates, preferential precipitation of other phases is often observed at grain boundaries, particularly α/γ interfaces. In this examination, the precipitates formed in a Nb-containing duplex stainless steel have been identified using analytical electron microscopy.
Proceedings, annual meeting, Electron Microscopy Society of America
Segregation of solute atoms to grain boundaries, dislocations, and other extended defects can occ... more Segregation of solute atoms to grain boundaries, dislocations, and other extended defects can occur under thermal equilibrium or non-equilibrium conditions, such as quenching, irradiation, or precipitation. Generally, equilibrium segregation is narrow (near monolayer coverage at planar defects), whereas non-equilibrium segregation exhibits profiles of larger spatial extent, associated with diffusion of point defects or solute atoms. Analytical electron microscopy provides tools both to measure the segregation and to characterize the defect at which the segregation occurs. This is especially true of instruments that can achieve fine (<2 nm width), high current probes and as such, provide high spatial resolution analysis and characterization capability. Analysis was performed in a Philips EM400T/FEG operated in the scanning transmission mode with a probe diameter of <2 nm (FWTM). The instrument is equipped with EDAX 9100/70 energy dispersive X-ray spectrometry (EDXS) and Gatan 6...
Proceedings, annual meeting, Electron Microscopy Society of America
The technological development of aluminum nitride (A1N) substrates is driven to a large extent to... more The technological development of aluminum nitride (A1N) substrates is driven to a large extent towards the economical production of high thermal conductivity sintered ceramics for substrate applications. Stringent demands on matrix purity combined with the practical necessity of sintering additives have led to extensive analyses of property controlling matrix defect structures and of the role of additives in both matrix purification and sintering. Of particular interest are defects such as inversion domain boundaries (IDBs) and grain boundaries which may serve as segregation sites for the dominant impurities in A1N, particularly oxygen. In this work quantitative methods of analytical electron microscopy are applied to the analysis of chemical segregation in electronic grade A1N.Energy dispersive x-ray spectroscopy (EDAX 9100) using a ∼2-nm-diam. probe (Philips EM400T/FEG) has revealed the segregation of yttrium and calcium to the grain boundaries of commercial Toshiba N-170 ceramics...
Proceedings, annual meeting, Electron Microscopy Society of America
Radiation-induced segregation (RIS) and associated irradiation-assisted stress corrosion cracking... more Radiation-induced segregation (RIS) and associated irradiation-assisted stress corrosion cracking (IASCC) of austenitic alloys may be a major factor in limiting component lifetimes in water-cooled nuclear reactors. There are some similarities between radiation-induced sensitization/IASCC and thermally-induced sensitization/intergranular stress corrosion cracking. Both processes are associated with chromium depletion at grain boundaries. Segregation to boundaries in a neutron irradiated type 316 stainless steel has been investigated with both energy-dispersive X-ray spectrometry (EDXS) and parallel detection electron energy loss spectrometry (PEELS).All specimens were from the same heat of cold-worked type 316 stainless steel. Both unirradiated control material and material irradiated at ∼300°C to a range of fluences 0.3 - 5 × 1026 neutrons/m2 (E>0.1 MeV) were available. The mass of irradiated material was minimized by mechanically polishing 3-mm-diam. disks to ∼75 μm thickness pr...
The Shared Research Equipment (SHaRE) User Facility and Program at Oak Ridge National Laboratory ... more The Shared Research Equipment (SHaRE) User Facility and Program at Oak Ridge National Laboratory (ORNL) provides microanalytical facilities for studies within the materials sciences. Available instrumentation includes advanced analytical electron microscopes, atom probe field ion microscopes, and nanoindentation facilities. Through SHaRE, researchers from U.S. universities, industries, and government laboratories may collaborate with Facility scientists to perform research not possible at their home institutions. International collaborations are also possible. Most SHaRE projects seek correlations at the microscopic or atomic scale between structure and properties in a wide range of metallic, ceramic, and other structural materials. Typical research projects include studies of magnetic materials, advanced alloys, catalysts, semiconductor device materials, high Tc superconductors, and surface-modified polymers. Projects usually involve one or more external researchers visiting the SH...
Whereas the spatial resolution for standard secondary electron (SEI) imaging in a scanning electr... more Whereas the spatial resolution for standard secondary electron (SEI) imaging in a scanning electron microscope or electron probe microanalyzer is related to the incident probe diameter, the spatial resolution for x-ray microanalysis is related to the convolution of the probe diameter with the spatial extent of the analyzed volume for a point probe. The latter is determined by electron scattering in the specimen and the subsequent emission of excited x-rays from the specimen. As such, it is possible that “What you see is not what you get”. This is especially true for instruments with high brightness electron sources (field emission). This problem is compounded by probe aberrations which at Gaussian image focus can produce significant electron tails extending tens of microns from the center of the probe.
Experiments and simulations show that the microstructural stability of nanocrystalline Cu can be ... more Experiments and simulations show that the microstructural stability of nanocrystalline Cu can be improved by adding impurity atoms, such as Sb, which migrate to the grain boundaries. Cu100-xSbx alloys are cast in three compositions (Cu-0.0, 0.2 and 0.5 at.%Sb) and subsequently processed into nanocrystalline form by equal channel angular extrusion (ECAE). The presence of Sb atoms at the grain boundaries
ABSTRACTTitanium nitride crystals were grown from titanium nitride powder on tungsten by the subl... more ABSTRACTTitanium nitride crystals were grown from titanium nitride powder on tungsten by the sublimation-recondensation technique. The bright golden TiN crystals displayed a variety of shapes including cubes, truncated tetrahedrons, truncated octahedrons, and tetrahedrons bounded by (111) and (100) crystal planes. The TiN crystals formed regular, repeated patterns within individual W grains that suggested epitaxy. X-ray diffraction and electron backscattering diffraction revealed that the tungsten foil was highly textured with a preferred foil normal of (100) and confirmed that the TiN particles deposited epitaxially with the orientation TiN(100)‖W(100) and TiN[100]‖W[110], that is, the unit cells of the TiN crystals were rotated 45° with respect to the tungsten. Because of its larger coefficient of thermal expansion compared to W, upon cooling from the growth temperature, the TiN crystals were under in-plane tensile strain, causing many of the TiN crystals to crack.
Multiple-walled carbon nanotubes (MWNTs) produced using the chemical vapor deposition method were... more Multiple-walled carbon nanotubes (MWNTs) produced using the chemical vapor deposition method were functionalized via attaching aminopolymer poly(propionylethylenimine-co-ethylenimine ) to the nanotubes. Two different reaction conditions based on acylating the ...
Uploads
Papers by Edward Kenik