Production and characterization of nanostructured Ti-based intermetallics

TiAl-X and TiAl₃-X alloys are produced by mechanical milling and sintered by a plasma assisted technique (X represents either Fe, Mn or Cr). Milling of elemental powder mixtures produces a homogeneous mixture consisting of crystallites immersed in an amorphous matrix. Sintering gives rise to a recrystallized single phase microstructure in the TiAl₃-X alloys with a nanometric grain size. Alloys in the system TiAl-X also show a fine grain size after consolidation. Two phases (α₂ (DO₁₉) and γ (Ll₀) are found finely dispersed. Compression test are used to investigate the deformation mechanism in the consolidated alloys. The TiAl₃-X alloys show no plasticity; fracture appears before any plastic behavior is observed at high stress levels. In the TiAl-X alloys plasticity is found in all cases together with high yield stresses. Analysis of the fracture surfaces (TiAl₃ alloys) and dislocation structures is used to discuss the deformation mechanism.