On the linear instability of the Rayleigh spheroidization process

Journal Article · Tue Jan 01 00:00:00 EST 1991 · Scripta Metallurgica; (United States)

DOI:https://doi.org/10.1016/0956-716X(91)90228-S· OSTI ID:5095505

Hackney, S A ^[1]

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1. Michigan Technological Univ., Houghton, MI (United States). Dept. of Metallurgical Engineering

The problem of diffusional stability of infinitely long cylinders with respect to spheroidization has been analyzed. It is well known that long solid cylinders will break down into individual particles of spherical geometry under the action of an appropriate shape perturbation. The driving force for this process is considered to be the chemical potential gradients associated with variations in curvature which develop on the surface, or interface, in response to the perturbation. The resulting diffusional flow of material can lead to a breakdown of the rod morphology. From a practical point of view, the cylindrical geometry is one which occurs in fiber reinforced composites and rod shaped precipitates in eutectic/eutectoid structures. The shape stability of such rods is an important aspect of high temperature mechanical behavior. The general method of study for this problem involves analyzing the time dependent behavior of a perturbation; which is an imposed, mass conserving and periodic surface wave of small amplitude. These surface undulations will be referred to here as Rayleigh surface waves. In most cases, attention is focused on the surface wavelength which gives the maximum growth rate of the perturbation. This choice has not been justified by experimental results on rod eutectics which show significant scatter in the instability wavelength, and little or no physical basis, such as a stability argument, has been presented for the operation of the maximum growth rate hypothesis in the growth of periodic Rayleigh surface waves. Despite the many detailed studies on the behavior of Rayleigh surface waves, the possibility that the surface waves themselves might actually be unstable has not been considered in the literature.

• OSTI ID: 5095505
• Journal Information: Scripta Metallurgica; (United States), Vol. 25:1; ISSN 0036-9748
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
COMPOSITE MATERIALS
CYLINDERS
REINFORCED MATERIALS
MECHANICAL PROPERTIES
RODS
MORPHOLOGY
CHEMICAL REACTION KINETICS
DIFFUSION
FLOW STRESS
HIGH TEMPERATURE
INTERFACES
RAYLEIGH WAVES
SHAPE
SURFACES
KINETICS
MATERIALS
REACTION KINETICS
SEISMIC SURFACE WAVES
SEISMIC WAVES
STRESSES
360603* - Materials- Properties
360602 - Other Materials- Structure & Phase Studies