Thermal neutron scattering on Fe-based amorphous Invar alloys

The generalized phonon spectra were measured for Fe-based amorphous metal-metal Fe90-xCoxZr10 (x=10,40), metal-metalloid Fe80-yCryP13C7 (y=4,8) alloys, and Fe86Co4Zr10 Invar alloy at different temperatures above or below the Curie temperature (Tc=330K) by using the neutron inelastic scattering method. From the comparison among the three phonon spectra, the phonon softening related to the Invar effect was observed. In connection with the acoustic-phonon softening in the crystalline Invar alloy, it can be inferred that the low-energy phonon softening is a common feature of Invar alloys, which is irrelevant to both the long-range order of crystalline and the type of materials, and might be attributed to be enhancement of electron-phonon interaction.