Kinetics and shape of crystal growth from the melt for substances with low L/kT values

Ovsienko, D. E.; Alfintsev, G. A.; Маслов, В. А.

doi:10.1016/0022-0248(74)90251-6

Cited by 60 publications

(19 citation statements)

References 2 publications

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“…In fact, the morphological change with increasing supercooling or driving forces similar to the present study has been reported in both experiment and simulation on crystal growth in a diffusion field [6,16,17,18,19]. For example, in the growth of snow crystals, both a diffusion process and a surface kinetic process are closely reflected in the variety of growth shape [19].…”

Section: Discussionsupporting

confidence: 56%

Growth shape of isotactic polystyrene crystals in thin films

Taguchi

Miyaji

Izumi

et al. 2001

Polymer

185

168

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The crystal growth of isotactic polystyrene (it-PS) is investigated in very thin, 11 nm thick films. The it-PS crystals grown in the thin films show quite different morphology from that in the bulk. With decreasing crystallization temperature, the branching morphology in a diffusion field appears: dendrite and compact seaweed. The branching morphology is formed through a morphological instability caused by the gradient of film thickness around a crystal; the thicker the film thickness, the larger the lateral growth rate of crystals. Regardless of the morphological change, the growth rate as well as the lamellar thickness depends on crystallization temperature as predicted by the surface kinetics.

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Section: Discussionsupporting

confidence: 56%

Growth shape of isotactic polystyrene crystals in thin films

Taguchi

Miyaji

Izumi

et al. 2001

Polymer

185

168

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“…Authors usually assume simple and unchanged morphologies of the growing shape (i.e., sphere, octahedron or stars with six orthotropic branches representing the ͗100͘ preferred dendrite growth directions) which enclose the mush and is fully surrounded by liq-uid. [9][10][11] These morphologies are based on experimental observation 12) and can eventually change with the local cooling conditions. 11,13) The kinetics models dedicated to the free growth in the undercooled melt consider dendrites growing in an infinite bath with a fixed undercooling, which is kept unchanged during growth.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study of the Transition from Constrained to Unconstrained Growth during Directional Solidification.

Gandin

2000

ISIJ International

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Temperature measurements are carried out in 99.99 wt% aluminium and aluminium-silicon alloys. The experimental apparatus was initially built for the study of microporosity formation in aluminium alloys.1) The construction is designed to obtain upward directional solidification by limiting lateral heat flow during cooling and suppressing fluid flow induced by the pouring sequence. Cooling occurs from the top part of the ingot, leading to the formation of a surface dendrite layer. In the 99.99 wt% aluminium, very few equiaxed grains sink down from the surface dendrite layer into the liquid. The density of the equiaxed dendritic grains is too low to block the columnar cellular front. Cooling curves show that, once superheat disappears (i.e., when no substantial thermal gradient remains in the liquid), the liquid is kept at an almost constant temperature during the growth of the columnar front and a small negative thermal gradient forms in the liquid ahead of the growing columnar front. It is concluded that the liquid is reheated by the growing columnar front. In the case of the aluminium-silicon alloys, a columnar-to-equiaxed transition (CET) is observed at almost twothirds of the ingot length. The columnar length is found to increase slightly with decreasing the solute content. Recalescence is measured in a fully equiaxed region, while cooling rate, recorded by the thermocouple located just above the CET, remains negative.

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“…Both the center and the size of the octahedron associated with a newly captured cell µ are initialized carefully in order to propagate the crystallographic orientation of the grain and to integrate correctly the dendrite tip growth kinetics using the local undercooling, ∆T t µ (Gandin et al 1997). The CA growth procedure has to verify that, after several steps and in a uniform temperature field, a simple octahedral shape is obtained with the correct misorientation with respect to the CA grid, in agreement with experimental observations (Ovsienko et al 1974). …”

Section: Growth Lawmentioning

confidence: 83%