scholarly journals Characterization of Phosphorus Segregation in Neutron-Irradiated Pressure Vessel Steels by Atom Probe Field Ion Microscopy

1994 ◽  
Vol 373 ◽  
Author(s):  
M. K. Miller ◽  
R. Jayaram ◽  
K.F. Russell
Keyword(s):  
Pressure Vessel ◽  
Boundary Segregation ◽  
Atom Probe ◽  
Probe Field ◽  
Phosphorus Segregation ◽  
Field Ion Microscopy ◽  
Narrow Region ◽  
Pressure Vessel Steels ◽  
Ion Microscopy

AbstractAn atom probe field ion microscopy characterization of A533B and Russian VVER 440 and 1000 pressure vessel steels has been performed to determine the phosphorus coverage of grain and lath boundaries. Field ion micrographs of grain and lath boundaries have revealed that they are decorated with a semi-continuous film of discrete brightly-imaging precipitates that were identified as molybdenum carbonitride precipitates. In addition, extremely high phosphorus levels were measured at the boundaries. The phosphorus segregation was found to be confined to an extremely narrow region indicative of monolayer-type segregation. The phosphorus coverages determined from the atom probe results of the unirradiated materials were in excellent agreement with predictions based on McLean's equilibrium model of grain boundary segregation. The boundary phosphorus coverage of a neutron-irradiated weld material was significantly higher than that observed in the unirradiated material.

Characterization of Internal Interfaces by Atom Probe Field Ion Microscopy

1992 ◽  
Vol 295 ◽  
Author(s):  
M. K. Miller ◽  
Raman Jayaram
Keyword(s):  
Grain Boundaries ◽  
Compositional Analysis ◽  
Atom Probe ◽  
Probe Field ◽  
Field Ion Microscopy ◽  
Surrounding Matrix ◽  
Wide Range ◽  
Ion Microscopy ◽  
Field Ion Microscope

AbstractThe near atomic spatial resolution of the atom probe field ion microscope permits the elemental characterization of internal interfaces, grain boundaries and surfaces to be performed in a wide variety of materials. Information such as the orientation relationship between grains, topology of the interface, and the coherency of small precipitates with the surrounding matrix may be obtained from field ion microscopy. Details of the solute segregation may be obtained at the plane of the interface and as a function of distance from the interface for all elements simultaneously from atom probe compositional analysis. The capabilities and limitations of the atom probe technique in the characterization of internal interfaces is illustrated with examples of grain boundaries and interphase interfaces in a wide range of materials including intermetallics, model alloys, and commercial steels.

scholarly journals Atomic Level Characterization of Neutron Irradiated Pressure Vessel Steels

2000 ◽  
Vol 650 ◽  
Author(s):  
M. K. Miller ◽  
P. Pareige
Keyword(s):  
Pressure Vessel ◽  
Three Dimensional ◽  
Atom Probe ◽  
Dislocation Loops ◽  
Probe Field ◽  
Pressure Vessel Steels ◽  
Spatial Coordinates ◽  
Radiation Induced ◽  
Nickel Manganese

ABSTRACTAtom probe tomography provides one of the most effective tools to characterize the solute distribution and precipitation that occurs in pressure vessel steels and associated model alloys during irradiation. The three-dimensional atom probe is able to experimentally determine the elemental identities of the atoms and their spatial coordinates with near atomic resolution so that their distribution within small volumes of the specimen can be reconstructed and analyzed. This technique together with conventional atom probe field ion microscopy has been applied to many different types of pressure vessel steels and model alloys and has revealed and characterized several different nanostructural transformations. These radiation induced or enhanced processes lead to the formation of copper-nickel-manganese-silicon-enriched precipitates, and solute segregation to dislocations, dislocation loops, nanovoids and boundaries.

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