The ternary alloy Tb0.3Dy0.7Fe2 (Terfenol-D) is of significant technological interest as it possesses the largest known magnetostriction to anisotropy ratio near room temperature. Results of microstructural and magnetic domain observations by Lorentz microscopy and reflection x-ray topography are presented from both stoichiometric twinned single crystals prepared by a free-standing zoning technique, and pseudo single crystals prepared by the Czochralski method. Direct evidence of wall interactions with dislocations, twin boundaries and precipitates are presented which demonstrate the complex interaction between the magnetic and strain energies within this material.

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Effect of B on the microstructure and magnetostriction of zoned Dy 0.7 Tb 0.3 Fe 1.95Liquid phase sintering of rare earth-iron (Dy0.7Tb0.3Fe2) magnetostrictive materialsThe ternary alloy Tbo.sDyc,,Fe2 (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 Fes). A bar with ( 111) and ( 170) faces perpendicular to the [ 1121 growth direction was examined. Also, a [l 1 l] slab was cut from the boule. This slab was studied along the [I li] and [liO] directions with prestress applied along the [l li]. This is the iirst report of the effects of applying prestress and magnetic fields in a direction not collinear with the [l 121 growth direction. From magnetization (M) and magnetostriction (A> measurements as a function of field, prestress, and temperature, we determined the hysteresis and saturation parameters. These measurements do not indicate the [ii01 il and 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 [ 1 li] 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 ( 170) bar faces and on the [l li] slab correlate with each other with respect to orientations and domain interpretations.