Dynamic Young modulus, torsion modulus and elastic energy dissipation were
measured in Ni(56.2)Fe(0.3)Al(43.1)Ta(0.)3Mo(0.1) (NiAl crystal) and Ni56.6
Fe12.3Al30.2Hf0.6(Al2O3)(0.3) (NiFeAl crystal). The elastic constant C' = (
C-11 - C-12)/2 has in both alloys a positive temperature derivative: (dC'/d
T)>0 from 150 K up to 1300 K. The elastic energy dissipation exhibits a Deb
ye-like peak whose activation energy is 2.36+/-0.05 eV in NiAl and 1.98+/-0
.09 eV in NiFeAl. The peak is described as a Zener's pair reorientation. (C
) 2000 Elsevier Science S.A. All rights reserved.