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Title:Three-dimensional flow instabilities during alloy solidification
Author(s):Baker, Carolyn F.; Riahi, Daniel N.
Subject(s):Alloy Solidification
Flow Instabilities
Abstract:Three-dimensional linear flow instabilities of oscillatory and stationary types and initial formation of chimneys in a mushy region during solidification of a binary alloy are investigated. Chimneys are vertical channels that can lead to freckles in the solidified material. Freckles are imperfections that interrupt the uniformity of the solidified material and cause areas of mechanical weakness. A stability analysis and numerical computations for deformed liquid-mush and deformed mush-solid interfaces provide information on portion of the neutral stability surface, velocity data and density data for the solid fraction perturbation in the mushy layer that leads to local regions of chimney formation. The results for the flow pattern in the form of steady and oscillatory hexagons indicate distinct hexagonal modes of steady and oscillatory convection. The importance and roles of these modes are discussed in relation to various flow features and chimney formation in the mushy layer, as well as to future nonlinear instability research with application to freckles elimination. The more critical instability modes detected in this study appear to be oscillatory hexagons in the form of standing waves.
Issue Date:1997-10
Publisher:Department of Theoretical and Applied Mechanics. College of Engineering. University of Illinois at Urbana-Champaign
Series/Report:TAM R 866
Genre:Technical Report
Rights Information:Copyright 1997 Board of Trustees of the University of Illinois
Date Available in IDEALS:2021-11-04

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  • Technical Reports - Theoretical and Applied Mechanics (TAM)
    TAM technical reports include manuscripts intended for publication, theses judged to have general interest, notes prepared for short courses, symposia compiled from outstanding undergraduate projects, and reports prepared for research-sponsoring agencies.

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