Domain observation and magnetostriction in Tb sub 0. 3 Dy sub 0. 7 Fe sub 2 twinned single crystals

• Published in: Journal of applied physics 1991-04, Vol.69:8
• Main Authors: Teter, J.P., Mahoney, K., Al-Jiboory, M., Lord, D.G., McMasters, O.D.
• Format: Article
• Language: English
• Subjects: 360102 - Metals & Alloys- Structure & Phase Studies; 360104 - Metals & Alloys- Physical Properties; ALLOY SYSTEMS; ALLOYS; DIAGRAMS; DOMAIN STRUCTURE; DYSPROSIUM ALLOYS; HYSTERESIS; IRON ALLOYS; MAGNETIC PROPERTIES; MAGNETIZATION; MAGNETOSTRICTION; MATERIALS SCIENCE; PHASE DIAGRAMS; PHYSICAL PROPERTIES; RARE EARTH ALLOYS; STOICHIOMETRY; TERBIUM ALLOYS; TERNARY ALLOY SYSTEMS; TWINNING
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.348938

The ternary alloy Tb{sub 0.3}Dy{sub 0.7}Fe{sub 2} (Terfenol-D) exhibits the largest known magnetostriction to anisotropy ratio near room temperature. To better determine the interaction between the elastic and magnetic properties of this material, a stoichiometric twinned single crystal was grown by a free-standing float-zone technique. Observations using Scanning electron microscopy and energy dispersive spectroscopy confirmed that the sample was free of the normally present rare-earth (RE) eutectic phase and simultaneously free of Widmanstatten precipitate (RE Fe{sub 3}). A bar with (111) and (1{bar 1}0) faces perpendicular to the (11{bar 2}) growth direction was examined. Also, a (11{bar 1}) slab was cut from the boule. This slab was studied along the (11{bar 1}) and (1{bar 1}0) directions with prestress applied along the (11{bar 1}). This is the first report of the effects of applying prestress and magnetic fields in a direction not collinear with the (11{bar 2}) growth direction. From magnetization ({ital M}) and magnetostriction ({lambda}) measurements as a function of field, prestress, and temperature, we determined the hysteresis and saturation parameters. These measurements do not indicate the (1{bar 1}0) {lambda} and {ital M} behaviors found previously for RE-rich Terfenol-D. Domain observations with differential phase contrast and x-ray topography have shown different orientations in the twin and parent sections of the (11{bar 1}) specimen. The observed structures can be interpreted as arising from domains with magnetization components normal to the surface. The domain observations on the (111) and (1{bar 1}0) bar faces and on the (11{bar 1}) slab correlate with each other with respect to orientations and domain interpretations.