Magnetic order, phonons, and martensitic transformation in the gamma-Fe72Ni6Mn22 alloy

Phonon dispersion curves were measured in a single crystal of the antifeffo magnetic gamma -Fe72Ni6Mn22 alloy, that suffers a gamma double right arrow epsilon martensitic transformation (M-s = 320 K). The results obtained are compared with the available data on phonon behavior in ferromagnetic gamma -FeNi and antiferromagnetic gamma -Fe70MW30 alloys near the gamma double ri ght arrow alpha and gamma double right arrow epsilon transitions. The latti ce dynamics of all these alloys was found to depend on the type of magnetic order. The effect of the magnetic state on the phonon behavior and martens itic transformations in these alloys is discussed.