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Persistence of 5:3 plates in RE5(SixGe1-x)4 alloys

Published online by Cambridge University Press:  03 March 2011

O. Ugurlu ,
L.S. Chumbley  and
C.R. Fisher
O. Ugurlu*
Affiliation:
Department of Materials Science and Engineering, Iowa State University, Ames, Iowa 50011; and Ames Laboratory (DOE), Iowa State University, Ames, Iowa 50011-3020
L.S. Chumbley
Affiliation:
Department of Materials Science and Engineering, Iowa State University, Ames, Iowa 50011; and Ames Laboratory (DOE), Iowa State University, Ames, Iowa 50011-3020
C.R. Fisher
Affiliation:
Department of Materials Science and Engineering, Iowa State University, Ames, Iowa 50011; and Ames Laboratory (DOE), Iowa State University, Ames, Iowa 50011-3020
*
a) Address all correspondence to this author. e-mail: ozan@iastate.edu
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Abstract

Studies of RE5(SixGe1-x)4 alloys, where RE equals rare earth, have revealed a second-phase having a thin-plate morphology in essentially every alloy examined, independent of exact composition and matrix crystal structure. Identified as having a composition approximating Gd5(SixGe1-x)3 and a hexagonal crystal structure in the Gd-based system, it has been suggested that the observed thin-plate second phases seen in this family of rare earth alloys are all most likely of the form RE5(SixGe1-x)3. A number of interesting observations suggest that the formation of these second-phase plates is somewhat unusual. The purpose of this article is to investigate the stability of this second phase in Gd- and Er-based compounds. The stability was investigated as a function of thermal cycling and large-scale composition fluctuations. The results of scanning and transmission electron microscopy (SEM, TEM) studies indicate that the RE5(SixGe1-x)3 phase is extremely stable once it forms in a RE5(SixGe1-x)4 matrix.

Keywords

Scanning electron microscopy (SEM)Second phasesTransmission electron microscopy (TEM)
Type
Articles
Information
Journal of Materials Research , Volume 21 , Issue 10 , October 2006 , pp. 2669 - 2674
Copyright
Copyright © Materials Research Society 2006

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