Plastic deformation of uniaxially aligned lamellar γ/α2 titanium aluminides containing chromium

Polysynthetically twinned uniaxially aligned lamellar binary and ternary γ/α2 titanium aluminides were deformed in uniaxial compression and investigated in the transmission electron microscope. The yield stress strongly depends on the orientation of the lamellae to the compression axis. For all investigated orientations, the yield stress of the ternary samples containing chromium is higher than that of the corresponding binary material. The yield stress decreases with increasing temperature. The deformation is mainly carried by ordinary dislocations 〈110] and (twinning) partial dislocations 1/6〈112] which are still active at high temperatures. If the lamellar interfaces are oriented parallel to the compression axis, deformation twinning is the main deformation process.