Growth rate of microdomains during phase separation by a two-step temperature jump

1993 ◽  
Vol 26 (15) ◽  
pp. 4047-4049 ◽  
Author(s):  
Kyu Dae Kwak ◽  
Mamoru Okada ◽  
Tsuneo Chiba ◽  
Takuhei Nose
Keyword(s):  
Growth Rate ◽  
Phase Separation ◽  
Temperature Jump

Phase separation in undercooled molten Pd80Si20: Part I

1999 ◽  
Vol 14 (9) ◽  
pp. 3653-3662 ◽  
Author(s):  
K. L. Lee ◽  
H. W. Kui
Keyword(s):  
Growth Rate ◽  
Phase Separation ◽  
Crystal Growth ◽  
Grain Refinement ◽  
Crystallization Temperature ◽  
Sharp Decrease ◽  
Nucleation And Growth ◽  
Crystal Growth Rate ◽  
Large Undercooling ◽  
Kinetic Crystallization

Three different kinds of morphology are found in undercooled Pd80Si20, and they dominate at different undercooling regimens ΔT, defined as ΔT = T1 – Tk, where T1 is the liquidus of Pd80Si20 and Tk is the kinetic crystallization temperature. In the small undercooling regimen, i.e., for ΔT ≤ 190 K, the microstructures are typically dendritic precipitation with a eutecticlike background. In the intermediate undercooling regimen, i.e., for 190 ≤ ΔT ≤ 220 K, spherical morphologies, which arise from nucleation and growth, are identified. In addition, Pd particles are found throughout an entire undercooled specimen. In the large undercooling regimen, i.e., for ΔT ≥ 220 K, a connected structure composed of two subnetworks is found. A sharp decrease in the dimension of the microstructures occurs from the intermediate to the large undercooling regimen. Although the crystalline phases in the intermediate and the large undercooling regimens are the same, the crystal growth rate is too slow to bring about the occurrence of grain refinement. Combining the morphologies observed in the three undercooling regimens and their crystallization behaviors, we conclude that phase separation takes place in undercooled molten Pd80Si20.

scholarly journals A computational study of surface-directed phase separation in polymer blends under temperature gradient

2021 ◽  
Author(s):  
Mohammad Tabatabaieyazdi
Keyword(s):  
Growth Rate ◽  
Phase Separation ◽  
Temperature Gradient ◽  
Long Range ◽  
Spinodal Decomposition ◽  
Surface Potential ◽  
Short Range ◽  
Computational Study ◽  
Polymeric Materials ◽  
Partial Wetting

To apprehend the real industrial behavior of polymeric materials phase separation phenomenon, the nonlinear Cahn-Hilliard theory incorporating the Flory-Huggins-de Gennes free energy theory was used to study the non-uniform thermal-induced phase separation phenomenon in a symmetric binary polymer blend in which surface(s) with short- and long-range attraction to one polymer component compete with temperature gradient effects. The numerical results indicate that an increase of diffusion coefficient value will increase the rate of phase separation in the bulk but will decrease the growth rate of the wetting layer on the surface regardless of the surface potential strength. Also, the morphology transition from complete to partial wetting of the surface with short range surface attraction is successfully demonstrated. However, no partial wetting is observed for the surface with long-range potential. For shallow quenches, first, a growth rate of t 0.5 is observed in the early stage of spinodal decomposition phase separation at the surface and then a decline in the growth rate to t 0.13 in the intermediate stage occurred. For short- and long-range surface potential, the growth rate value of t 0.33 obtained in the bulk. The morphology results of temperature gradient effect on surface directed spinodal decomposition in short-range, long- range and multiple-surface attraction cases have been presented for the first time. It is realized that regardless of surface potential magnitude, surface enrichment is increased by higher temperature gradient (deep quenches on the side with no surface attraction). The studied models would provide more in depth understanding of polymer blendiprocesses.

Phase Separation Induced by Two Step Temperature Jump.

1992 ◽  
Vol 24 (2) ◽  
pp. 215-218 ◽  
Author(s):  
Mamoru Okada ◽  
Kyu Dae Kwak ◽  
Takuhei Nose
Keyword(s):  
Phase Separation ◽  
Temperature Jump

MBE growth of compound semiconductors: Part II. Applications of the stochastic model

1992 ◽  
Vol 7 (5) ◽  
pp. 1235-1242 ◽  
Author(s):  
R. Venkatasubramanian
Keyword(s):  
Growth Rate ◽  
Surface Roughness ◽  
Phase Separation ◽  
Stochastic Model ◽  
Diffusion Process ◽  
Surface Diffusion ◽  
Growth Front ◽  
Mbe Growth ◽  
Temperature Range ◽  
Kinetics Of

In this part of the work (Part II), two typical applications of the stochastic model to the MBE growth kinetic studies are presented. The applications are the MBE growth kinetics of a hypothetical compound semiconductor, ab, and diamond cubic alloy, ax. In this study, the effect of the surface diffusion process on the MBE growth kinetics is analyzed. In the case of the compound, ab, the results of the present stochastic model are compared with that of a Monte Carlo simulation study in the temperature range of 600–850 K. The results of the two studies agree qualitatively. Higher substrate temperatures result in higher growth rate and growth front smoothness due to higher surface diffusion. Beyond 800 K, the growth rate and the growth front smoothness become independent of temperature because of the saturation of the interlayer diffusion process. In the case of the alloy studies, the kinetics of a hypothetical diamond cubic alloy in which the thermodynamics favors phase separation, is studied in the temperature range of 573–898 K. Below 648 K, due to negligible surface diffusion, there is no clustering of the alloy, but the surface roughness is very large. In the intermediate temperature range of 573–798 K, with increasing temperature, the surface diffusion increases, resulting in more clustering and less surface roughness. Above 798 K, due to very high surface diffusion, complete phase separation of the alloy and a smooth surface result.

scholarly journals A computational study of surface-directed phase separation in polymer blends under temperature gradient

2021 ◽  
Author(s):  
Mohammad Tabatabaieyazdi
Keyword(s):  
Growth Rate ◽  
Phase Separation ◽  
Temperature Gradient ◽  
Long Range ◽  
Spinodal Decomposition ◽  
Surface Potential ◽  
Short Range ◽  
Computational Study ◽  
Polymeric Materials ◽  
Partial Wetting

To apprehend the real industrial behavior of polymeric materials phase separation phenomenon, the nonlinear Cahn-Hilliard theory incorporating the Flory-Huggins-de Gennes free energy theory was used to study the non-uniform thermal-induced phase separation phenomenon in a symmetric binary polymer blend in which surface(s) with short- and long-range attraction to one polymer component compete with temperature gradient effects. The numerical results indicate that an increase of diffusion coefficient value will increase the rate of phase separation in the bulk but will decrease the growth rate of the wetting layer on the surface regardless of the surface potential strength. Also, the morphology transition from complete to partial wetting of the surface with short range surface attraction is successfully demonstrated. However, no partial wetting is observed for the surface with long-range potential. For shallow quenches, first, a growth rate of t 0.5 is observed in the early stage of spinodal decomposition phase separation at the surface and then a decline in the growth rate to t 0.13 in the intermediate stage occurred. For short- and long-range surface potential, the growth rate value of t 0.33 obtained in the bulk. The morphology results of temperature gradient effect on surface directed spinodal decomposition in short-range, long- range and multiple-surface attraction cases have been presented for the first time. It is realized that regardless of surface potential magnitude, surface enrichment is increased by higher temperature gradient (deep quenches on the side with no surface attraction). The studied models would provide more in depth understanding of polymer blendiprocesses.

Structure Pinning During Phase-Separation of Polyamide/Ionomer Blends

1996 ◽  
Vol 461 ◽  
Author(s):  
R. A. Weiss ◽  
Y. Feng ◽  
R. Tucker ◽  
R. Xie ◽  
C. C. Han ◽  
...  
Keyword(s):  
Phase Separation ◽  
Temperature Jump ◽  
Separation Process ◽  
Temperature Dependent ◽  
Sulfonated Polystyrene ◽  
Thermally Induced ◽  
Phase Separation Process ◽  
Phase Separation Kinetics ◽  
Spinodal Region ◽  
Separation Kinetics

ABSTRACTBlends of lightly sulfonated polystyrene and poly(N,N'-dimethylethylene sebacamide) (Li-SPS/mPA) are miscible as a result of strong ion-amide complexation. The blends exhibit LCST phase behavior and an increase of the sulfonation level from 4 to 9.5 mol% raises the critical temperature by 150°C. Phase separation may be thermally induced and isthermodynamically reversible. The phase separation kinetics that occur following a temperature-jump deep into the spinodal region of the phase diagram deviate from conventional Cahn-Hilliard theory and the phase separation process stalls after a couple of hours, essentially pinning the structure at that point. The extent of phase-separation that occurs before pinning is temperature-dependent.

Sign in / Sign up

Export Citation Format

Share Document