Abstract
Inelastic neutron scattering techniques have been used to measure the phonon dispersion curves of bcc
Fe1?xGax x=10.8, 13.3, 16.0, 22.5 alloys as a function of Ga concentration. The phonon frequencies of every
branch were found to decrease significantly with increasing Ga concentration. The softening was most pronounced
for the T2 0 branch and, to a lesser extent, the L branch in the vicinity of = 2 3. The
concentration dependence of the shear elastic constant C =1/2 C11?C12 , calculated from the slope of the
T2 0 branch, was found to agree with the results of sound velocity measurements. For the higher concentration
sample measured, 22.5 at. % Ga, new branches appeared, an effect associated with the increase in the
number of atoms per unit cell.
