Slow equilibration in systems undergoing diffusion-controlled phase separation on a lattice

1986 ◽  
Vol 33 (3) ◽  
pp. 1823-1829 ◽  
Author(s):  
Gene F. Mazenko ◽  
Oriol T. Valls
Keyword(s):  
Phase Separation ◽  
Diffusion Controlled

Kinetics of Phase Separation in Lithium Bearing HLW Alkaliborosilicate Glasses

1995 ◽  
Vol 412 ◽  
Author(s):  
J. GÖttlicher ◽  
H. J. Pentinghaus
Keyword(s):  
Phase Separation ◽  
Transformation Temperature ◽  
Ostwald Ripening ◽  
Metastable Phase ◽  
Particle Growth ◽  
Glass Frit ◽  
Diffusion Controlled ◽  
Metastable Phase Separation ◽  
Scale Particle ◽  
Kinetics Of

AbstractA TEM study on the kinetics of metastable phase separation in a lithium bearing HLW glass frit is presented. As nothing was known about the kinetics of metastable phase separation below the glass transformation temperature we had to carry out annealing experiments just above and below the transformation temperature, in order to achieve phase separation on a laboratory time scale- Particle growth in the WAKID5 HLW glass frit at 550 °C occurs by a diffusion controlled Ostwald ripening process (about 40 °C above Tg). Metastable phase separation in the lithium bearing glasses even at lower temperatures cannot be excluded from the present study. In NaBSi3O8 glass (Tg ≈ 580 °C) phase separation could be detected at 500 °C well below Tg after about 160 days.

Effect of SiO2 nanoparticles on the reaction-induced phase separation in dynamically asymmetric epoxy/PEI blends

RSC Advances ◽  
2015 ◽  
Vol 5 (11) ◽  
pp. 8471-8478 ◽  
Author(s):  
Weizhen Li ◽  
Zonglian Xia ◽  
Ao Li ◽  
Yang Ling ◽  
Baoyu Wang ◽  
...  
Keyword(s):  
Phase Separation ◽  
Sio2 Nanoparticles ◽  
Diffusion Controlled ◽  
Scaling Coefficient

The scaling coefficient α decreases significantly when the epoxy/PEI blend is filled with certain concentration of MEK–SiO2 nanoparticles, implying that the nanoparticles are forcing the coarsening mechanism towards the diffusion-controlled regime.

scholarly journals An Application of the Cahn-Hilliard Approach to Smoothed Particle Hydrodynamics

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
M. Hirschler ◽  
M. Huber ◽  
W. Säckel ◽  
P. Kunz ◽  
U. Nieken
Keyword(s):  
Phase Separation ◽  
Boundary Conditions ◽  
Smoothed Particle Hydrodynamics ◽  
Sph Method ◽  
Free Surfaces ◽  
Diffusion Controlled ◽  
Universal Power Law ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Solid Walls

The development of a methodology for the simulation of structure forming processes is highly desirable. The smoothed particle hydrodynamics (SPH) approach provides a respective framework for modeling the self-structuring of complex geometries. In this paper, we describe a diffusion-controlled phase separation process based on the Cahn-Hilliard approach using the SPH method. As a novelty for SPH method, we derive an approximation for a fourth-order derivative and validate it. Since boundary conditions strongly affect the solution of the phase separation model, we apply boundary conditions at free surfaces and solid walls. The results are in good agreement with the universal power law of coarsening and physical theory. It is possible to combine the presented model with existing SPH models.

Bulk standards for low-temperature biological x-ray microanalysis

1984 ◽  
Vol 42 ◽  
pp. 282-283
Author(s):  
P. Echlin ◽  
M. McKoon ◽  
E.S. Taylor ◽  
C.E. Thomas ◽  
K.L. Maloney ◽  
...  
Keyword(s):  
Phase Separation ◽  
Low Temperature ◽  
Analytical Method ◽  
Salt Solutions ◽  
Absolute Concentration ◽  
Cooling Process ◽  
X Ray ◽  
The Absolute ◽  
Analytical Procedures ◽  
Electrical Conductors

Although sections of frozen salt solutions have been used as standards for x-ray microanalysis, such solutions are less useful when analysed in the bulk form. They are poor thermal and electrical conductors and severe phase separation occurs during the cooling process. Following a suggestion by Whitecross et al we have made up a series of salt solutions containing a small amount of graphite to improve the sample conductivity. In addition, we have incorporated a polymer to ensure the formation of microcrystalline ice and a consequent homogenity of salt dispersion within the frozen matrix. The mixtures have been used to standardize the analytical procedures applied to frozen hydrated bulk specimens based on the peak/background analytical method and to measure the absolute concentration of elements in developing roots.

A TEM investigation of a hyper-eutectic lead-tin alloy

1988 ◽  
Vol 46 ◽  
pp. 562-563
Author(s):  
John A. Sutliff
Keyword(s):  
Volume Diffusion ◽  
Eutectic Mixture ◽  
Precipitation Reaction ◽  
Directionally Solidified ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Diffusion Controlled ◽  
Discontinuous Precipitation Reaction ◽  
Controlled Precipitation

Near-eutectic Pb-Sn alloys are important solders used by the electronics industry. In these solders, the eutectic mixture, which solidifies last, is the important microstructural consituent. The orientation relation (OR) between the eutectic phases has previously been determined for directionally solidified (DS) eutectic alloys using x-ray diffraction or electron chanelling techniques. In the present investigation the microstructure of a conventionally cast, hyper-eutectic Pb-Sn alloy was examined by transmission electron microscopy (TEM) and the OR between the eutectic phases was determined by electron diffraction. Precipitates of Sn in Pb were also observed and the OR determined. The same OR was found in both the eutectic and precipitation reacted materials. While the precipitation of Sn in Pb was previously shown to occur by a discontinuous precipitation reaction,3 the present work confirms a recent finding that volume diffusion controlled precipitation can also occur.Samples that are representative of the solder's cast microstructure are difficult to prepare for TEM because the alloy is multiphase and the phases are soft.

Phase separation in sol gel-derived ceramic films of silica-zirconia, alumina-zirconia, and titania-zirconia system

1994 ◽  
Vol 52 ◽  
pp. 646-647
Author(s):  
J. Tong ◽  
L. Eyring
Keyword(s):  
Fracture Toughness ◽  
Phase Separation ◽  
Sol Gel ◽  
Great Influence ◽  
High Strength ◽  
Chemical Durability ◽  
Separation Method ◽  
Toughening Mechanism ◽  
Ceramic Films ◽  
Zirconia Toughened Alumina

There is increasing interest in composites containing zirconia because of their high strength, fracture toughness, and its great influence on the chemical durability in glass. For the zirconia-silica system, monolithic glasses, fibers and coatings have been obtained. There is currently a great interest in designing zirconia-toughened alumina including exploration of the processing methods and the toughening mechanism.The possibility of forming nanocrystal composites by a phase separation method has been investigated in three systems: zirconia-alumina, zirconia-silica and zirconia-titania using HREM. The morphological observations initially suggest that the formation of nanocrystal composites by a phase separation method is possible in the zirconia-alumina and zirconia-silica systems, but impossible in the zirconia-titania system. The separation-produced grain size in silica-zirconia system is around 5 nm and is more uniform than that in the alumina-zirconia system in which the sizes of the small polyhedron grains are around 10 nm. In the titania-zirconia system, there is no obvious separation as was observed in die alumina-zirconia and silica-zirconia system.

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