Magnetic domains and microstructural defects in Terfenol-D

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.