Terfenol: A study of the phase equilibrium diagram and the solidification process

Thesis/Dissertation · Mon Dec 06 23:00:00 EST 1993

DOI:https://doi.org/10.2172/10112286· OSTI ID:10112286

Anderson, Mary ^[1]

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1. Iowa State Univ., Ames, IA (United States)

Terfenol is a rare earth-iron alloy that was first developed at the Naval Ordinance Laboratory because of its rare magnetostrictive properties. Terfenol is composed of terbium and dysprosium combined with iron in a composition Tb_xDy_1-xFe₂, where x~0.3. The objective of this work was to determine the growth characteristics of Terfenol and its dependence on solidification rate, temperature gradient, and stoichiometry. Specific goals of this work were to verify the phase equilibria that is currently accepted for the systems DyFe₂ and TbFe₂, and establish the phase equilibria near the composition Tb_0.3Dy_0.7Fe₂; establish that Terfenol grows directly from the liquid and that the reaction is occurring under metastable conditions; evaluate whether or not Terfenol can be grown under plane front conditions with a new radiofrequency float zone apparatus, and; determine whether or not <111> seeded crystals can be grown and <111> single crystals produced by elimination of dendrites employing growth methods capable of achieving high gradient/solidification rate ratios.

• Research Organization: Ames Lab., IA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 10112286
• Report Number(s): IS-T--1688; ON: DE94004883
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360101
360102
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201
CHEMICAL AND PHYSICOCHEMICAL PROPERTIES
CRYSTALLIZATION
DIFFERENTIAL THERMAL ANALYSIS
DYSPROSIUM ALLOYS
IRON BASE ALLOYS
MAGNETOSTRICTION
METALLOGRAPHY
PHASE DIAGRAMS
PHASE STUDIES
PREPARATION AND FABRICATION
SCANNING ELECTRON MICROSCOPY
SOLIDIFICATION
STRUCTURE AND PHASE STUDIES
TERBIUM ALLOYS
TERNARY ALLOY SYSTEMS