Static and Dynamic Displacements in α-Phase FeCr

Abstract

ABSTRACTA single crystal of α-Fe0.47Cr0.53 was annealed at 1100K, 5K above the a-phase transition temperature, for four days and then water quenched. A detailed investigation using X-ray synchrotron radiation was previously carried out to study the short-range order and static displacements in this alloy. The phonon dispersion curves, studied here by inelastic neutron scattering, appear typical of bcc alloys and the phonon groups are observed to be significantly broadened in the vicinity of the dip at ξ=2/3 in the longitudinal [ξ ξ ξ] phonon dispersion. In this paper we explore the possibility that nearly random concentration fluctuations and an extremely small difference in the atomic sizes, together with an appropriate lattice response function, can nonetheless produce elastic diffuse scattering indicative of a new phase.