Topic
Directional solidification
About: Directional solidification is a research topic. Over the lifetime, 6177 publications have been published within this topic receiving 90781 citations.
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TL;DR: In this article, a scaling law is shown to exist between the secondary dendrite arm spacing, λ2, near the tip and the Dendrite tip radius, p, which is λ 2/ρ = 2.2 ± 0.3.
Abstract: Directional solidification experiments have been carried out in a succinonitrile-5.5 mol pct acetone system to characterize dendrite tip radius and interdendrite spacings as functions of growth rate and temperature gradient in the liquid. A maximum in primary dendrite spacing as a function of growth rate is observed, and this maximum is found to occur at the dendrite-cellular transition velocity. A scaling law is shown to exist between the secondary dendrite arm spacing, λ2, near the tip and the dendrite tip radius, p, which is λ2/ρ = 2.2 ± 0.3. Experimental results on ρ have been found to agree with the theoretical model based on the marginal stability criterion.
252 citations
TL;DR: In this paper, two techniques for melttexture processing Ba2YCu3O6.5 by directional solidification from a semisolid melt containing particles of BaY2CuO5 and a copper-rich liquid were reported.
Abstract: Experiments are reported on two techniques for melt‐texture processing Ba2YCu3O6.5 by directional solidification from a semisolid melt containing particles of BaY2CuO5 and a copper‐rich liquid. One of these employs an electric resistance furnace with ambient or oxygen enriched atmosphere; the other is a laser‐heated furnace operating at 1.3 atm oxygen. Solidification interface morphologies and other structural features were examined in quenched specimens. Depending on growth rate and temperature gradient, three different types of growth morphologies of the growing 123 phase were observed: ‘‘faceted plane front,’’ ‘‘cellular dendritic’’ or ‘‘equiaxed blocky.’’ The interface temperature decreased markedly with increasing growth rate for the faceted plane front specimens. In the remaining specimens, solidification took place over a range of temperatures. The temperature of the ‘‘root’’ of the solidification front dropped, but temperature of the solidification front ‘‘tip’’ did not. A solidification model is ...
249 citations
15 Jun 1997-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, an appropriate theoretical model is developed to determine the conditions under which nucleation can occur in the liquid close to a moving solid-liquid interface for both, low and high interface velocities.
Abstract: During directional solidification of an alloy, it is possible to nucleate the growing phase or a new phase at or ahead of the interface. This is critical in the phase selection, in the columnar to equiaxed transition under casting, welding or rapid solidification conditions and the formation of bands in peritectic systems. Following Hunt, an appropriate theoretical model is developed to determine the conditions under which nucleation can occur in the liquid close to a moving solid-liquid interface for both, low and high interface velocities. At high growth rates, non-equilibrium effects are shown to play an important role in predicting such transitions.
237 citations
TL;DR: In this paper, it was found that streaming of solute-enriched liquid at the tip of high-order branches promotes growth by local undercooling, which causes solute pile-up at the roots of the branches.
236 citations
TL;DR: In this article, the diffusion-limited-aggregation model is generalized in order to take into account the surface effects playing an essential role during most of the growth processes, and with variation of a parameter of the model the geometry of the clusters generated in the Monte Carlo simulations gradually changes from the randomly branched diffusion limited aggregation clusters into compact, nearly regular, snowflakelike patterns.
Abstract: The diffusion-limited-aggregation model is generalized in order to take into account the surface effects playing an essential role during most of the growth processes. With variation of a parameter of the model the geometry of the clusters generated in the Monte Carlo simulations gradually changes from the randomly branched diffusion-limited-aggregation clusters into compact, nearly regular, snowflakelike patterns. The deposition of particles along a line results in patterns similar to those observed in the experiments on directional solidification.
219 citations