Structure of Ti-50%Nb-8%Al and Ti-65%Nb-8%Al-2%Cu alloys

Methods of transmission electron microscopy and X-ray diffraction analysis have been applied to study structure and phase composition in Ti-50%Nb-8%Al and Ti-65%Nb-8%Al-2%Cu alloys. It is shown that at constant Al concentration the ordering in quenched β-matrix and B2-structure decomposition on annealing proceed more actively in the alloy with 50%Nb. Decomposition of quenched $β+B2)-structure happens with ordered phase precipitation according to the mechanism of nucleation and grain growth with particle shape varying from equiaxial to laminated one. Low cold reduction (2%) of quenched alloy promotes formation of homogeneous structure morphology on subsequent annealing. 6 refs., 6 figs