Quasicrystals and other metastable phases in rapidly quenched titanium-manganese alloys

Icosahedral quasicrystalline phase with m35 point group symmetry has been observed to occur in rapidly quenched Ti-37 at % manganese and Ti-24 at % Mn-13 at % Fe alloys. The occurrence of this phase is confirmed by the 5-3-2 fold electron diffraction patterns. In addition to the sharp diffraction spots, diffuse intensity maxima is also observed in the diffraction patterns of these alloys. Upon annealing, the diffuse intensity maxima tend to become sharper. The occurrence of diffuse intensity is presently explained by two different approaches viz anisotropic phason strain present in the quenched state and in terms of a rational approximant structure. In addition to the icosahedral quasicrystalline phase ,other metastable phases13; like retained beta, rational approximant structure and a decagonal like phase are also observed in these alloys