Icosahedral phase formation in Ti_68-xCr₃₂Si_xalloys

Abstract

Abstract We report, for the first time, the formation of the icosahedral phase (i-phase) in rapidly quenched Ti68-xCr32Six alloys, where 69 ≤ x ≤ 18. The i-phase occurs at a composition for which there are no structurally similar crystalline phases. Transmission electron microscopy (TEM) and X-ray diffraction measurements are presented. The TEM diffraction patterns show strong localized diffuse scattering and spot anisotropy. These features are compared with similar ones found in Al83Cr17 and Ti61Mn37Si2 icosahedral phases. No evidence for an enthalpic signature of phase transformation was found upon heating to the melting temperature, indicating that the i-phase is at least strongly metastable. The first estimates of the density are reported.