Spinodal Decomposition in Fe-Cr-Co Alloys

1982 ◽  
Vol 21 ◽  
Author(s):  
S. S. Brenner ◽  
P. P. Camus ◽  
M. K. Miller ◽  
W. A. Soffa
Keyword(s):  
Phase Separation ◽  
Spinodal Decomposition ◽  
Atom Probe ◽  
Continuous Phase ◽  
Miscibility Gap ◽  
Two Phase ◽  
Probe Field ◽  
Long Wavelength ◽  
Composition Fluctuations ◽  
Kinetics Of

Continuous phase separation or spinodal decomposition occurs within a miscibility gap through the selective amplification of long wavelength concentration waves to produce a two-phase modulated microstructure. To comprehensively study the formation of these modulated microstructures and the kinetics of continuous phase separation the behavior of the composition fluctuations in the decomposing material should be monitored directly. The atom probe field-ion microscope is an ideal instrument for this type of investigation of fine-scale microstructures because of its ultra-high spatial resolution and microchemical analysis capability.

A Comparison of Tem and Apfim to the Interpretation of Modulated Microstructures

1985 ◽  
Vol 43 ◽  
pp. 70-71
Author(s):  
M.G. Burke ◽  
M.K. Miller
Keyword(s):  
Low Temperature ◽  
Microstructural Characterization ◽  
Superlattice Reflection ◽  
High Volume ◽  
Atom Probe ◽  
Dark Field ◽  
Miscibility Gap ◽  
Second Phase ◽  
Two Phase ◽  
Probe Field

Interpretation of fine-scale microstructures containing high volume fractions of second phase is complex. In particular, microstructures developed through decomposition within low temperature miscibility gaps may be extremely fine. This paper compares the morphological interpretations of such complex microstructures by the high-resolution techniques of TEM and atom probe field-ion microscopy (APFIM).The Fe-25 at% Be alloy selected for this study was aged within the low temperature miscibility gap to form a <100> aligned two-phase microstructure. This triaxially modulated microstructure is composed of an Fe-rich ferrite phase and a B2-ordered Be-enriched phase. The microstructural characterization through conventional bright-field TEM is inadequate because of the many contributions to image contrast. The ordering reaction which accompanies spinodal decomposition in this alloy permits simplification of the image by the use of the centered dark field technique to image just one phase. A CDF image formed with a B2 superlattice reflection is shown in fig. 1. In this CDF micrograph, the the B2-ordered Be-enriched phase appears as bright regions in the darkly-imaging ferrite. By examining the specimen in a [001] orientation, the <100> nature of the modulations is evident.

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.

On the kinetics of phase separation in aqueous two-phase systems

1998 ◽  
Vol 711 (1-2) ◽  
pp. 319-329 ◽  
Author(s):  
M.H Salamanca ◽  
J.C Merchuk ◽  
B.A Andrews ◽  
J.A Asenjo
Keyword(s):  
Phase Separation ◽  
Two Phase ◽  
Aqueous Two Phase Systems ◽  
Phase Systems ◽  
Kinetics Of

scholarly journals Phase Separation Behavior and System Properties of Aqueous Two-Phase Systems with Polyethylene Glycol and Different Salts: Experiment and Correlation

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Haihua Yuan ◽  
Yang Liu ◽  
Wanqian Wei ◽  
Yongjie Zhao
Keyword(s):  
Phase Separation ◽  
Sodium Citrate ◽  
Line Length ◽  
Continuous Phase ◽  
Two Phase ◽  
Separation Rate ◽  
Aqueous Two Phase Systems ◽  
Phase Systems ◽  
System Properties ◽  
Tie Line

The phase separation behaviors of PEG1000/sodium citrate, PEG4000/sodium citrate, PEG1000/ammonium sulfate, and PEG4000/ammonium sulfate aqueous two-phase systems were investigated, respectively. There are two distinct situations for the phase separation rate in the investigated aqueous two-phase systems: one state is top-continuous phase with slow phase separation rate and strong bottom-continuous phase with fast phase separation rate and weak volume ratio dependence. The system properties such as density, viscosity, and interfacial tension between top and bottom phases which have effects on the phase separation rate of aqueous two-phase systems were measured. The property parameter differences between the two phases increased with increasing tie line length and then improved the phase separation rate. Moreover, a modified correlation equation including the phase separation rate, tie line length, and physical properties of the four aqueous two-phase systems has been proposed and successfully tested in the bottom-continuous phase, whose coefficients were estimated through regression analysis. The predicted results of PEG1000/sodium citrate aqueous two-phase systems were verified through the stationary phase retention in the cross-axis countercurrent chromatography.

Kinetics of phase separation by spinodal decomposition in mixtures of telechelic hydroxy-terminated polyisobutylene and poly(tetrahydrofuran)

1991 ◽  
Vol 24 (17) ◽  
pp. 4852-4856 ◽  
Author(s):  
Hak Soo Lee ◽  
Thein Kyu ◽  
Avi Gadkari ◽  
Joseph P. Kennedy
Keyword(s):  
Phase Separation ◽  
Spinodal Decomposition ◽  
Kinetics Of

Kinetics of phase separation at the early stage of spinodal decomposition in epoxy resin modified with PEI blends

2008 ◽  
Vol 287 (1) ◽  
pp. 23-28 ◽  
Author(s):  
Wenjun Gan ◽  
Yingfeng Yu ◽  
Xiaoyun Liu ◽  
Minghai Wang ◽  
Shanjun Li
Keyword(s):  
Phase Separation ◽  
Epoxy Resin ◽  
Spinodal Decomposition ◽  
Early Stage ◽  
Kinetics Of

The Measurement of Composition During the Early Stages of the Spinodal Decomposition of Fe-Cr Alloys

1990 ◽  
Vol 186 ◽  
Author(s):  
M.G. Hetherington ◽  
J.M. Hyde ◽  
M.K. Miller
Keyword(s):  
Monte Carlo ◽  
Phase Separation ◽  
Spinodal Decomposition ◽  
Atom Probe ◽  
Statistical Techniques ◽  
Fine Scale ◽  
Monte Carlo Calculations ◽  
Early Stages ◽  
Non Linear

AbstractThe properties of many advanced alloys are derived from extremely fine-scale microstructures. This poses interesting questions about the measurement of composition on this scale. The phase separation of model Fe-Cr alloys has been been studied with the atom-probe. Statistical techniques have been used to estimate the composition and compare the results with the predictions of linear and non-linear theories of spinodal decomposition and the distributions obtained from Monte-Carlo calculations.

Hydrogen-Induced Phase Separation of Palladium-Rhodium Alloys Using an Environmental Cell TEM

1997 ◽  
Vol 3 (S2) ◽  
pp. 591-592
Author(s):  
D.F. Teter ◽  
R.D. Field ◽  
D.J. Thoma
Keyword(s):  
Phase Separation ◽  
Hydrogen Absorption ◽  
Melt Spinning ◽  
Room Temperature ◽  
Annealing Treatment ◽  
Miscibility Gap ◽  
Environmental Cell ◽  
Cold Rolled ◽  
Kinetics Of

The palladium-rhodium system has been extensively studied for its hydrogen absorption characteristics. However, the phase diagram of the palladium-rhodium system has not been conclusively determined below 800 K. Shield and Williams have experimentally determined the incoherent miscibility gap in Pd-Rh alloys using electrical resistivity studies, however the coherent miscibility gap and spinodal have not been determined. Recently work by Noh and Flanagan has suggested that hydrogen enhances metal atom mobility and may increase the kinetics of phase separation in Pd-Rh alloys. Field and Thoma found that hydrogen causes a Pd-10%Rh alloy to decompose during an in situhydrogen charging experiment in an environmental cell TEM. According to the calculations by Gonis et al. of the miscibility gap for the palladium-rhodium system, the Pd-10%Rh alloy may be within the chemical spinodal at room temperature.In this work, two palladium-rhodium compositions were investigated. The first was a Pd-10 at.% Rh alloy produced by melt-spinning, and the second was a Pd-30at.%Rh alloy which had been arc-melted and cold rolled followed by an annealing treatment to homogenize the material. TEM specimens were prepared by punching 3 mm disks from the material.

Phase Separation and Precipitation in a PH 17-4 Stainless Steel By Prolonged Aging At 400 °C

1998 ◽  
Vol 4 (S2) ◽  
pp. 96-97 ◽  
Author(s):  
M. Murayama ◽  
Y. Katayama ◽  
K. Hono
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Phase Separation ◽  
Power Plants ◽  
Atom Probe ◽  
Industrial Applications ◽  
Precipitation Reaction ◽  
Medium Temperature ◽  
Probe Field ◽  
Prolonged Aging

Precipitation-hardened stainless steels are important structural materials in a variety of industrial applications in aircraft, chemical and power plants. These steels have a combination of good mechanical properties, corrosion resistance and simple fabrication process. Precipitation reaction in a PH 17-4 stainless steel which contains approximately 3 wt.% of Cu begins with formation of coherent copper-rich precipitate, which subsequently transform to incoherent fee Cu by further aging. By prolonged aging at 400 °C, embrittlement occurs as hardening progresses. Both the coarsening of Cu and the decomposition of the martensite matrix could be the reasons for this embrittlement. Thus, this study attempted to clarify the phase separation and the precipitation processes in a PH 17-4 stainless steel on prolonged aging by atom probe field ion microscopy (APFIM), in order to understand the mechanism of the degradation of mechanical properties by long term medium temperature aging.

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