材料期刊网

Deformation-induced gamma -> DI-alpha(2) phase transformation was verified to occur in the twin-intersection region of a Ti-45Al-8Nb (at.%) alloy compressed at room temperature. High-resolution image observations of the deformation-induced DI-alpha(2) phase suggested that the orientation relationship between the DI-alpha(2) and gamma phases remained the typical one: (0001)(DI-alpha 2)//{111}(gamma), [11 (2) over bar0](DI-alpha 2)//< 101]gamma. The conversion of stacking sequence from ordered face-centered tetragonal to ordered nonequilibrium hexagonal close-packed structure was accomplished by the movement of a/6 < 11 (2) over bar] Shockley partial dislocations on every other {111}(gamma) plane. Compositional analysis based on energy dispersive spectra revealed that the DI-alpha(2) phase had the same composition as the matrix gamma phase. No compositional diffusion Occurred because the plastic deformation was carried out at room temperature. The strong stress concentration in the intersection region was the major force to induce the gamma -> DI-alpha(2) phase transformation in the process of room-temperature compression.