Formation of Bulk Nanostructured Materials by Rapid Solidification

2000 ◽  
Vol 15 (7) ◽  
pp. 1605-1611 ◽  
Author(s):  
W. H. Guo ◽  
L. F. Chua ◽  
C. C. Leung ◽  
H. W. Kui
Keyword(s):  
Surface Tension ◽  
Rapid Solidification ◽  
Spinodal Decomposition ◽  
Liquid State ◽  
Nanostructured Material ◽  
Synthesis Process ◽  
Undercooled Liquid ◽  
Metastable Liquid ◽  
Characteristic Wavelength ◽  
Eutectic Melt

When a eutectic melt is undercooled below its liquidus T1 by a critical amount, it undergoes metastable liquid-state spinodal decomposition. The resulting morphologies can be described as intermixing undercooled liquid networks of characteristic wavelength λ. At a temperature substantially below T1, λ can be <100 nm. When λ ≤ 100 nm, the undercooled liquid networks break up into nanometer-size droplets/strips driven apparently by surface tension. The morphologies of the tiny droplets/strips can be frozen by subsequent crystallization. The as-crystallized specimen is a nanostructured material. It is microvoid free and the size of the constituent grains is rather uniform. Two systems, Pd40.5Ni40.5P19 and Pd82Si18, were chosen to illustrate the synthesis process.

Crystallization of undercooled liquid spinodals: Part II

1999 ◽  
Vol 14 (9) ◽  
pp. 3663-3667 ◽  
Author(s):  
K. L. Lee ◽  
H. W. Kui
Keyword(s):  
Phase Separation ◽  
Latent Heat ◽  
Spinodal Decomposition ◽  
Liquid State ◽  
Morphological Changes ◽  
Microstructural Analysis ◽  
The Other ◽  
Undercooled Liquid ◽  
Metastable Liquid ◽  
Undercooled Melt

We demonstrated in “Phase separation in undercooled molten Pd80Si20: Part I” that when a molten Pd80Si20 ingot is undercooled into its undercooling regimen with ΔT ≥ 220 K (ΔT = T1 – T, where T1 is the liquidus and T is the temperature of the undercooled melt), liquid-state phase separation by spinodal decomposition occurs. On crystallization, one of the metastable liquid spinodals becomes Pd3Si, whereas the other one turns into Pd9Si2. In both cases, Pd particles precipitate out. Microstructural analysis indicates the Pd3Si subnetwork forms first. It then acts as a seed for the subsequent crystallization of the remaining undercooled melt, which finally forms the Pd9Si2 dendrites. As crystallization proceeds, latent heat and volume contraction bring about morphological changes.

Metastable liquid phase separation in undercooled molten Pd40.5Ni40.5P19

1997 ◽  
Vol 12 (2) ◽  
pp. 314-317 ◽  
Author(s):  
C. W. Yuen ◽  
K. L. Lee ◽  
H. W. Kui
Keyword(s):  
Phase Separation ◽  
Spinodal Decomposition ◽  
Liquid State ◽  
Microstructural Analysis ◽  
Nucleation And Growth ◽  
Transition Regime ◽  
Metastable Liquid ◽  
Temperature Liquid ◽  
Kinetic Crystallization ◽  
Metastable Liquid Phase Separation

It was demonstrated that molten Pd40.5Ni40.5P19 undergoes liquid state phase separation in the undercooling regime δT = T1 − T where T1 is the liquidus of Pd40.5Ni40.5P19 and T is the kinetic crystallization temperature. Liquid state phase separation by nucleation and growth takes place for δT ≤ 60 K while that by spinodal decomposition occurs for δT ≥ 100 K. Microstructural analysis of the undercooled specimen obtained in the undercooling regime of 60 ≤ δT ≤ 100 K indicates that it is the transition regime. Finally, it was found that when undercooled molten Pd40.5Ni40.5P19 undergoes liquid state spinodal decomposition, it first decomposes into two liquid networks, which is finally replaced by a system of three liquid networks.

Formation of bulk magnetic nanostructured Fe40Ni40P14B6 alloys by metastable liquid state phase separation

1999 ◽  
Vol 581 ◽  
Author(s):  
Q. Li ◽  
H.W. Kui
Keyword(s):  
Phase Separation ◽  
Spinodal Decomposition ◽  
Eutectic Alloy ◽  
Liquid State ◽  
Decomposition Reaction ◽  
Metastable Liquid ◽  
The One

ABSTRACTMETGLAS alloy #2826 (Fe40Ni40P14B6) is a eutectic alloy. Its melt can undergo metastable liquid state spinodal decomposition deep in the undercooling regime ΔT defined as ΔT = T1 - T where T1 is the liquidus of the alloy and T is the temperature at which the decomposition reaction takes place. Micrographs of undercooled Fe40Ni40P14B6 of ΔT = 209, 260 and 307 K were displayed. All of them exhibit refined microstructures, esp. the one with the largest ΔT.

Synthesis of 2-Hydroxyl-3-Sulfonic Acid Sodium Salt-Propyl Lacrylate

2012 ◽  
Vol 512-515 ◽  
pp. 2262-2266
Author(s):  
Rong Ming Zhang ◽  
Yue Wang ◽  
Wei Li ◽  
Hong Man Shan
Keyword(s):  
Surface Tension ◽  
Sodium Salt ◽  
Sulfonic Acid ◽  
Synthesis Method ◽  
Influence Factors ◽  
Synthesis Process ◽  
Step Process ◽  
Tension Tests ◽  
Acid Sodium Salt ◽  
Sulfonic Acid Sodium Salt

2-hydroxyl-3-sulfonic acid sodium salt-propyl lacrylate was synthesized through the three-step process (sulfonation, ring-closing reaction, and esterification) by using epichlorohydrin as the starting material. The structure of oxiranemethane sulfonic acid sodium salt and end product 2-hydroxyl-3-sulfonic acid sodium salt-propyl lacrylate was identified by FTIR and Melting point. The influence factors of the synthesis process were studied. The optimal condition of the synthesis of ring-closing reaction and esterification was gained. Through the synthesis method, a corresponding synthesis of lauric acid, 14 acid, palmitic acid, 18 acid were gained. Then they were on the surface tension tests to determine the critical micelle concentration.

Synthesis of Myristyl Sulpho Betaine Type Amphoteric Surfactant

2012 ◽  
Vol 455-456 ◽  
pp. 1217-1220
Author(s):  
Rong Ming Zhang ◽  
Zhen Yu Zhang ◽  
Hong Man Shan ◽  
Yue Wang
Keyword(s):  
Surface Tension ◽  
Reaction Time ◽  
Critical Micelle Concentration ◽  
Optimal Condition ◽  
Influence Factors ◽  
Starting Material ◽  
Amphoteric Surfactant ◽  
Synthesis Process ◽  
Tension Tests

A kind of novel betaine type amphoteric surfactant was synthesized using tetradecylamine and pentaerythritol as the starting material. The influence factors of the synthesis process were studied.The optimal condition of the synthesis was gained. The results have show that the reaction time and mole ratio (Dimethyl tetradecyl tertiary/ Intermediate) were 16h and 1.2/1 at 120°C.The structure of myristyl sulpho betaine type amphoteric surfactant was identified by FTIR.Then it was performed the surface tension tests to determine the critical micelle concentration (cmc).

The LSW model for Ostwald ripening with kinetic undercooling

2000 ◽  
Vol 130 (6) ◽  
pp. 1337-1361 ◽  
Author(s):  
Barbara Niethammer
Keyword(s):  
Surface Tension ◽  
Liquid Phase ◽  
Field Model ◽  
Ostwald Ripening ◽  
Solid Phase ◽  
Mean Field ◽  
Undercooled Liquid ◽  
Small Particles ◽  
Mean Field Model ◽  
Kinetic Undercooling

We study a Stefan problem for coarsening of many small particles of solid phase in undercooled liquid phase which includes surface tension and kinetic undercooling effects. A mean-field model is derived by homogenization of the free boundary problem. It extends the classical theory of Lifshitz et al. by taking into account effects due to kinetic undercooling.

Bubble instability in overheated liquid Helium-3

2014 ◽  
Vol 28 (28) ◽  
pp. 1450221
Author(s):  
V. M. Kolomietz
Keyword(s):  
Surface Tension ◽  
Liquid Helium ◽  
Bubble Radius ◽  
Memory Effects ◽  
Relaxation Processes ◽  
Vapor Bubbles ◽  
Metastable Liquid ◽  
Short Relaxation Time ◽  
Helium 3 ◽  
Surface Distortions

The generation and the growth of vapor bubbles in metastable liquid Helium-3 are studied. The finite diffuse layer of vapor bubble, the temperature dependence of the surface tension and the relaxation processes are taken into consideration. We show that the growth of bubble in overheated liquid Helium-3 is significantly influenced by the memory effects caused by the dynamic Fermi-surface distortions. In particular, the increase of bubble is strongly hindered and accompanied by the characteristic oscillations of the bubble radius. The oscillations of the bubble radius disappear in a short relaxation-time limit where the memory effects are negligible.

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