Grain refinement induced by a critical crystal growth velocity in undercooled melts

1990 ◽  
Vol 56 (4) ◽  
pp. 324-326 ◽  
Author(s):  
R. Willnecker ◽  
D. M. Herlach ◽  
B. Feuerbacher
Keyword(s):  
Crystal Growth ◽  
Grain Refinement ◽  
Growth Velocity ◽  
Undercooled Melts

Nucleation and Dendritic Growth in Undercooled Melts

1995 ◽  
Vol 398 ◽  
Author(s):  
Dieter M. Herlach
Keyword(s):  
Crystal Growth ◽  
Growth Velocity ◽  
Dendritic Growth ◽  
Magnetic Ordering ◽  
Containerless Processing ◽  
Magnetic Alloys ◽  
Dendrite Growth Velocity ◽  
Direct Measurements ◽  
Undercooled Melt ◽  
Undercooled Melts

ABSTRACTTechniques of containerless processing are applied to undercool and solidify metals and alloys. These techniques allow direct measurements of both the undercooling and the crystal growth velocity. Experimental results are presented for studies of nucleation of metastable crystalline phases and quasicrystals. Measurements of the dendrite growth velocity as a function of undercooling are exemplified for dilute Ni-based alloys and intermetallics. The results are analysed within current theories of rapid crystal growth. Their consequences on the formation of grain refined microstructures are highlighted. In addition, recent experiments on the undercooling of magnetic alloys are discussed revealing the existence of long-range magnetic ordering in an undercooled melt.

A Phase Field Model for Grain Refinement in Deeply Undercooled Metallic Melts

2001 ◽  
Vol 677 ◽  
Author(s):  
A.M. Mullis ◽  
R.F. Cochrane
Keyword(s):  
Grain Refinement ◽  
Phase Field ◽  
Growth Velocity ◽  
Morphological Changes ◽  
Phase Field Model ◽  
Side Branch ◽  
Kinetic Undercooling ◽  
Self Similar ◽  
Metallic Melts ◽  
Undercooled Melts

ABSTRACTWe present the results of phase field simulations of dendritic growth into pure undercooled melts, at growth velocities up to 35 m s−1. We find that, at low growth velocities, dendrite morphologies are broadly self-similar with increasing growth velocity. However, above ≈ 15 m s−1 the initiation of side-branching moves closer to the dendrite tip with increasing growth velocity. This appears to be related to the level of kinetic undercooling at the tip. Once side- branch initiation begins to occur within 1-2 radii of the tip, profound morphological changes occur, leading to severe thinning of the dendrite trunk and ultimately repeated multiple tip- splitting. This process can be invoked to explain many of the observed features of spontaneous grain refinement in deeply undercooled metallic melts.

Crystal growth velocity of sodium salt hydrates

1983 ◽  
Vol 28 (1) ◽  
pp. 19-23 ◽  
Author(s):  
Dan D. Edie ◽  
Charles G. Sandell ◽  
Joseph C. Mullins
Keyword(s):  
Crystal Growth ◽  
Sodium Salt ◽  
Growth Velocity ◽  
Salt Hydrates

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.

Defect-mediated crystal growth from deeply undercooled melts

2022 ◽  
Vol 201 ◽  
pp. 110861
Author(s):  
Zhenzhen Yan ◽  
Bin Xu ◽  
Jinfu Li ◽  
Lingti Kong
Keyword(s):  
Crystal Growth ◽  
Undercooled Melts

Critical Behavior of Crystal Growth Velocity

1991 ◽  
Vol 16 (2) ◽  
pp. 195-200 ◽  
Author(s):  
H Löwen ◽  
J Bechhoefer
Keyword(s):  
Crystal Growth ◽  
Critical Behavior ◽  
Growth Velocity

scholarly journals Ice Growth Acceleration by Antifreeze Proteins Leads to Higher Thermal Hysteresis Activity

2020 ◽  
Author(s):  
Jinzi Deng ◽  
Elana Apfelbaum ◽  
Ran Drori
Keyword(s):  
Crystal Growth ◽  
Growth Inhibition ◽  
Growth Velocity ◽  
Crystal Morphology ◽  
Thermal Hysteresis ◽  
Antifreeze Proteins ◽  
Ice Crystal ◽  
Ice Growth ◽  
Thermal Hysteresis Activity ◽  
Adsorption Rates

<p>Since some antifreeze proteins and glycoproteins (AF(G)Ps) cannot directly bind to all crystal planes, they change ice crystal morphology by minimizing the area of the crystal planes to which they cannot bind until crystal growth is halted. Previous studies found that growth along the <i>c</i>-axis (perpendicular to the basal plane, the crystal plane to which these AF(G)Ps cannot bind) is accelerated by some AF(G)Ps, while growth of other planes is inhibited. The effects of this growth acceleration on crystal morphology and on the thermal hysteresis activity are unknown to date. Understanding these effects will elucidate the mechanism of ice growth inhibition by AF(G)Ps. Using cold stages and an Infrared laser, ice growth velocities and crystal morphologies in AF(G)P solutions were measured. Three types of effects on growth velocity were found: concentration-dependent acceleration, concentration-independent acceleration, and concentration-dependent deceleration. Quantitative crystal morphology measurements in AF(G)P solutions demonstrated that adsorption rate of the proteins to ice plays a major role in determining the morphology of the bipyramidal crystal. These results demonstrate that faster adsorption rates generate bipyramidal crystals with diminished basal surfaces at higher temperatures compared to slower adsorption rates. The acceleration of growth along the <i>c</i>-axis generates crystals with smaller basal surfaces at higher temperatures leading to increased growth inhibition of the entire crystal.<a></a></p>

Direct Measurement of Crystal Growth Velocity in Epitaxial Phase-Change Material Thin Films

2019 ◽  
Vol 11 (44) ◽  
pp. 41544-41550 ◽  
Author(s):  
Mario Behrens ◽  
Andriy Lotnyk ◽  
Jürgen W. Gerlach ◽  
Martin Ehrhardt ◽  
Pierre Lorenz ◽  
...  
Keyword(s):  
Thin Films ◽  
Crystal Growth ◽  
Phase Change ◽  
Phase Change Material ◽  
Direct Measurement ◽  
Growth Velocity ◽  
Change Material
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