A large remanent strain was observed in free-standing float-zone Terfenol-D samples, following the application of a magnetic field or compressive stress. Such strains were considered to comprise 2 parts, leading to reversible or irreversible domain contributions to magnetostriction. The irreversible part corresponded to the magnetostrictive jump effect which belonged to non-180º domain wall motion. The reversible part contributed to slower changes in magnetostriction. When no stress was applied, the specimen exhibited a jump field of 21 and 53Oe for 180º and non-180º domain-wall motion, respectively. The jump field, distribution width and hysteresis field for non-180º domain-wall motion all increased with increasing stress; thus indicating the occurrence of complicated interactions between magnetic domains and defects. Stacking faults were often found, using electron microscopy, to act as domain-wall pinning centres. Scanning-probe microscopy showed that specific domain configurations formed around excess rare-earth, twin boundaries and grain boundaries; due to induced stresses and demagnetization effects.

Influence of Defects on Magnetostrictive Performance in Terfenol-D. X.G.Zhao, D.G.Lord, C.A.Faunce: Journal of Applied Physics, 2000, 87[9], 6286-8