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

• Published in: Journal of materials research Vol. 21; no. 10; pp. 2669 - 2674
• Main Authors: Ugurlu, O., Chumbley, L.S., Fisher, C.R.
• Format: Journal Article
• Language: English
• Published: New York, USA Cambridge University Press 01-10-2006
• Subjects: ALLOYS; MATERIALS; MATERIALS SCIENCE; PLATES; Scanning electron microscopy (SEM); Second phases; Transmission electron microscopy (TEM); Second phases; Scanning electron microscopy (SEM); Transmission electron microscopy (TEM)
• ISSN: 0884-2914; 2044-5326
• DOI: 10.1557/jmr.2006.0326

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.