TEM study on the formation of intragranular α precipitates in the Ti−16Nb alloy

The phase transformation mechanism leading to the formation of intragranular α precipitates in Ti−16Nb (at.%) alloy was investigated by TEM. Spinodal decomposition of the β matrix acts as the uniformly distributed heterogeneous nucleation sites for such α precipitates upon annealing at 550 °C. An α-like atomic arrangement with severe lattice distortion forms in the bcc lattice at the early stage of phase transformation and it transforms to the perfect hcp atomic structure gradually in a displacive mode.