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A New Analytical Approach to Predict Spacing Selection in Lamellar and Rod Eutectic SystemsThe Jackson and Hunt (JH) theory has been modified to relax the assumption of isothermal solid liquid interface used in their treatment. Based on the predictions of this modified theory, the traditional definitions of regular and irregular eutectics are revised. For regular eutectics, the new model identifies a range of spacing within the limits defined by the minimum undercooling of the a and beta phases. For the irregular Al-Si eutectic system, two different spacing selection mechanisms were identified: (1) for a particular growth rate, a nearly isothermal interface can be achieved at a unique minimum spacing lambda (sub t); (2) the average spacing (lambda (sub av) greater than lambda (sub t) is essentially dictated by the undercooling of the faceted phase. Based on the modified theoretical model, a semiempirical expression has been developed to account for the influence of the temperature gradient, which is dominant in the irregular Al-Si system. The behavior of the Fe-Fe3C eutectic is also discussed. The theoretical calculations have been found to be in good agreement with the published experimental measurements.
Document ID
20030108682
Acquisition Source
Headquarters
Document Type
Reprint (Version printed in journal)
Authors
Catalina, Adrian V.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Sen, Subhayu
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Stefanescu, Doru M.
(Alabama Univ. Tuscaloosa, AL, United States)
Date Acquired
August 21, 2013
Publication Date
February 1, 2003
Publication Information
Publication: Metallurgical and Materials Transactions A
Volume: 34A
Subject Category
Metals And Metallic Materials
Distribution Limits
Public
Copyright
Other

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