Direct observation of solidification microstructures around absolute stability

Journal Article · Sun Sep 01 04:00:00 EDT 1996 · Acta Materialia

DOI:https://doi.org/10.1016/1359-6454(95)00448-3· OSTI ID:389815

Ludwig, A; Kurz, W ^[1]

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1. Swiss Federal Inst. of Tech., Lausanne (Switzerland). Dept. of Materials

This paper presents, for the first time, experimental evidence for absolute stability in a transparent alloy. The succinonitrile-argon system was used to investigate the morphological transition from a cellular to a planar solid-liquid interface at high solidification velocities. Directional solidification of the organic contained in thin capillary tubes was observed in situ with an optical microscope. At the maximum interface velocity of 1.5 mm/s, a reduction of the solute content of the alloy resulted in a morphological transition from a cellular to a planar growth front. This transition developed in three stages: (1) transition from deep cylindrical cells to mixed patterns of cylindrical and elongated cells; (ii) transition from cylindrical and elongated cells to low amplitude cells; (iii) transition from low amplitude cells to plane front. Within the limits of uncertainties with respect to the material properties and the thermal gradient, correspondence between the experimental results on plane front transition and linear stability theory exists. It is shown that the transitions observed are located in the region near the limit point of the neutral stability curve on the branch for absolute morphological stability.

• OSTI ID: 389815
• Journal Information: Acta Materialia, Journal Name: Acta Materialia Journal Issue: 9 Vol. 44; ISSN 1359-6454; ISSN ACMAFD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALLOYS
ARGON
INTERFACES
LIQUIDS
MICROSTRUCTURE
MORPHOLOGY
NITRILES
OPTICAL MICROSCOPY
SIMULATION
SOLIDIFICATION
SOLIDS
SUCCINIC ACID
TEMPERATURE GRADIENTS
VELOCITY