Magnetomechanical effects in textured polycrystalline Tb76Dy24

Uniaxial stress-strain measurements were performed on polycrystalline Tb76D y24 alloys which exhibit "giant magnetostriction" at cryogenic temperatures . The Young's moduli were reduced by up to a factor of five at 77 K, in com parison to their values at 300 K. We attribute this reduction to a mechanic al compliance from domain rotation. Large mechanical hysteresis is also fou nd in nominally elastic stress-strain curves measured below the Curie tempe rature. Hysteretic curves from 0 to 25 MPa demonstrate up to 19% dissipatio n of the applied mechanical energy. The anisotropy of thermal expansion was also measured and used as a parameter for the degree of crystallographic t exture. This anisotropy was correlated to bulk magnetostriction and to mech anical hysteresis. (C) 2000 American Institute of Physics. [S0021-8979(00)1 6408-4].