A combined AEM/APFIM characterization of alloy X-750

1992 ◽  
Vol 50 (1) ◽  
pp. 174-175
Author(s):  
M.G. Burke ◽  
M.K. Miller
Keyword(s):  
Mechanical Properties ◽  
Analytical Electron Microscopy ◽  
Atom Probe ◽  
Alloy Development ◽  
Probe Field ◽  
Surrounding Matrix ◽  
The Matrix ◽  
Size And Morphology ◽  
Field Ion Microscope

In the development of advanced alloys for power system applications, the primary emphasis is placed on attaining specific mechanical properties with resistance to environmental attack. An important part of alloy development is the detailed characterization of the microstructure, because it is the composition, size and morphology of the microstructural features that define the mechanical properties of the material. The good mechanical properties of Ni-base superalloys are a result of the formation of fine coherent precipitates. In addition, other coarser phases may form which can degrade the properties of the alloys. Analytical electron microscopy (AEM) provides important information concerning the type and distribution of the phases in the alloys, but quantitative microchemical analysis of the ultra-fine precipitates is not readily obtainable with conventional AEM techniques. The high spatial resolution of the atom probe field-ion microscope (APFIM) makes this technique ideally suited to the analysis of the ultra-fine precipitates and surrounding matrix. The analysis of the matrix is particularly important in predicting the subsequent ageing response of the alloy, as previously shown in a detailed AEM/APFIM examination of Alloy 718. In this paper, a combined AEM/APFIM study of precipitation in Alloy X-750 is presented.

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 the Morphology of Phases in Chromindur Magnetic Alloys

1991 ◽  
Vol 232 ◽  
Author(s):  
M. K Miller ◽  
P. P. Camus ◽  
M. G. Hetherington
Keyword(s):  
Atom Probe ◽  
Heat Treatments ◽  
Miscibility Gap ◽  
Probe Field ◽  
Magnet Alloy ◽  
Two Phases ◽  
Isothermal Heat Treatments ◽  
Field Ion Microscope ◽  
Permanent Magnet Alloy

ABSTRACTThe atom probe field ion microscope has been used to characterize the morphology and determine the compositions of the iron-rich a and chromium-enriched α′ phases produced during isothermal and step cooled heat treatments in a Chromindur II ductile permanent magnet alloy. The good magnetic properties of this material are due to a combination of the composition of the two phases and the isolated nature and size of the ferromagnetic a phase. The morphology of the a phase is produced as a result of the shape of the miscibility gap and the step-cooled heat treatment and is distinctly different from that formed during isothermal heat treatments.

scholarly journals Combined Atom-Probe and Electron Microscopy Characterization of Fine Scale Structures in Aged Primary Coolant Pipe Stainless Steel

1986 ◽  
Vol 82 ◽  
Author(s):  
J. Bentley ◽  
M. K. Miller
Keyword(s):  
Electron Microscopy ◽  
Analytical Electron Microscopy ◽  
Atom Probe ◽  
Primary Coolant ◽  
Probe Field ◽  
Α Phase ◽  
Complementary Nature ◽  
Microscopy Characterization

ABSTRACTThe capabilities and complementary nature of atom probe field-ion microscopy (APFIM) and analytical electron microscopy (AEM) for the characterization of finescale microstructures are illustrated by examination of the changes that occur after long term thermal aging of cast CF 8 and CF 8M duplex stainless steels. In material aged at 300 or 400°C for up to 70,000 h, the ferrite had spinodally decomposed into a modulated fine-scaled interconnected network consisting of an iron-rich α′ phase and a chromium-enriched α phase with periodicities of between 2 and 9 nm. G-phase precipitates 2 to 10 nm in diameter were also observed in the ferrite at concentrations of more than 1021 m−3. The reported degradation in mechanical properties is most likely a consequence of the spinodal decomposition in the ferrite.

scholarly journals Specimen preparation of irradiated materials for examination in the atom probe field ion microscope

1994 ◽  
Vol 52 ◽  
pp. 882-883
Author(s):  
K. F. Russell ◽  
M. K. Miller
Keyword(s):  
Neutron Irradiation ◽  
Atom Probe ◽  
Specimen Preparation ◽  
Fine Scale ◽  
Probe Field ◽  
Taper Angle ◽  
Ion Microscopy ◽  
Remote Operations ◽  
Field Ion Microscope

The atom probe field ion microscope (APFIM) is well suited to the characterization of the fine scale features and defects that are formed in materials due to exposure to neutron irradiation. However, in order for the technique to be effective, suitable specimens are required. Atom probe field ion microscopy specimens are in the form of ultrasharp needles that are usually produced by a series of mechanical and chemical or electrochemical methods. These needles have a typical end radius of approximately 10 to 50 nm and a taper angle of between 1 and 5. The small dimensions mean that the specimens are extremely fragile and difficult to handle and do not easily lend themselves to remote operations in a hot cell. The small size and mass of the APFIM specimen has the advantage that the amount of material required is minimal.A concept in working with irradiated materials is to keep exposure to the operator "as low as reasonably achievable" (ALARA).

Applications of atom-probe field-ion microscopy to the study of interfaces

1993 ◽  
Vol 51 ◽  
pp. 862-863
Author(s):  
M.G. Burke ◽  
M.K. Miller
Keyword(s):  
Analytical Electron Microscopy ◽  
Atom Probe ◽  
Pressure Vessels ◽  
Low Alloy Steels ◽  
Probe Field ◽  
Microchemical Analysis ◽  
Elemental Sensitivity ◽  
Alloy Steels ◽  
Field Ion Microscope ◽  
Microstructural Studies

The near-atomic resolution and elemental sensitivity of the atom probe field-ion microscope (APFIM) permit the detailed microstructural and microchemical analysis of phases and interfaces in a variety of materials. To overcome the limitation of this technique in terms of volume of material sampled, it is frequently necessary to perform complementary microstructural studies by other techniques such as analytical electron microscopy (AEM) or auger electron spectroscopy (AES). With such complementary data, the microstructural significance of the APFIM data can be exploited. In addition to specifically evaluating segregation at interfaces, the high spatial resolution of the APFIM technique can be used to determine microcompositional fluctuations in the vicinity of interfaces. In this overview, some selected examples illustrating the application of the APFIM technique to the evaluation of segregation to interfaces are presented.Considerable research has been performed on low alloy steels, particularly those such as A533B which are used in the pressure vessels of nuclear reactors.

Microstructure Characterization of Tungsten Based Alloys for Fusion Application

2013 ◽  
Vol 58 (2) ◽  
pp. 473-476 ◽  
Author(s):  
G. Cempura ◽  
A. Kruk ◽  
C. Thomser ◽  
M. Wirtz ◽  
A. Czyrska-Filemonowicz
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Electron Tomography ◽  
Analytical Electron Microscopy ◽  
Large Scatter ◽  
Fine Grained ◽  
Analytical Electron ◽  
The Matrix ◽  
Strengthening Particles

The microstructure of two tungsten based alloys (W-1.1%TiC and W-1.7% TiC) was characterized using light microscopy, analytical electron microscopy and electron tomography. These alloys represent a class of W based dispersion strengthened alloys with TiC used as strengthening particles. Addition of TiC leads to improved creep resistance and tensile strength of the W based alloys. The results show that the W-1.7%TiC alloy exhibits large scatter in grain size, much higher porosity and contains also Ti-O particles. The W-1.1%TiC alloy has fine grained microstructure with uniformly distributed fine TiC particles within the matrix and low porosity. As a result of the different microstructure, the W-1.1%TiC alloy exhibits better mechanical properties, when compared to the W-1.7%TiC alloy.

Decomposition in Pd40Ni40P20 Bulk Metallic Glass

1998 ◽  
Vol 554 ◽  
Author(s):  
M. K. Miller ◽  
R. B. Schwarz ◽  
Yi He
Keyword(s):  
Phase Separation ◽  
Metallic Glass ◽  
Cast Alloy ◽  
Atom Probe ◽  
Probe Field ◽  
3 Dimensional ◽  
Short Range Ordering ◽  
Field Ion Microscope ◽  
Temperature Crystallization

AbstractAn atom probe field ion microscope and 3-dimensional atom probe characterization of the solute distribution in a bulk Pd40Ni40P20 metallic glass in the as-cast state and after annealing has been performed. Statistical analysis of the atom probe atom-by-atom data detected the presence of short range ordering in the as-cast alloy. Phase separation at the nanometer level is observed in glassy samples after annealing above the glass-transition temperature. Crystallization proceeds by phase separation into three distinct crystalline phases. Atom probe analysis of the alloy annealed for 1 h at 410°C revealed that the primary nickel phosphide phase contained significant levels of palladium, the palladium-rich Pd3P phosphide phase contained low levels of nickel and there was a small amount of a palladium-nickel solid solution.

Fabrication and characterization - by High Resolution Electron Microscopy and atom probe microanalysis - of Co-based metallic multilayer films

1990 ◽  
Vol 48 (4) ◽  
pp. 772-773
Author(s):  
Amanda K. Petford-Long ◽  
A. Cerezo ◽  
M.G. Hetherington
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Atom Probe ◽  
Multilayer Films ◽  
Interface Roughness ◽  
Probe Field ◽  
Resolution Electron ◽  
Potential Applications ◽  
Field Ion Microscope

The fabrication of multilayer films (MLF) with layer thicknesses down to one monolayer has led to the development of materials with unique properties not found in bulk materials. The properties of interest depend critically on the structure and composition of the films, with the interfacial regions between the layers being of particular importance. There are a number of magnetic MLF systems based on Co, several of which have potential applications as perpendicular magnetic (e.g Co/Cr) or magneto-optic (e.g. Co/Pt) recording media. Of particular concern are the effects of parameters such as crystallographic texture and interface roughness, which are determined by the fabrication conditions, on magnetic properties and structure.In this study we have fabricated Co-based MLF by UHV thermal evaporation in the prechamber of an atom probe field-ion microscope (AP). The multilayers were deposited simultaneously onto cobalt field-ion specimens (for AP and position-sensitive atom probe (POSAP) microanalysis without exposure to atmosphere) and onto the flat (001) surface of oxidised silicon wafers (for subsequent study in cross-section using high-resolution electron microscopy (HREM) in a JEOL 4000EX. Deposi-tion was from W filaments loaded with material in the form of wire (Co, Fe, Ni, Pt and Au) or flakes (Cr). The base pressure in the chamber was around 8×10−8 torr during deposition with a typical deposition rate of 0.05 - 0.2nm/s.

Sign in / Sign up

Export Citation Format

Share Document