Effect of Ti₂Cu precipitates on mechanical behavior of Ti-2.5Cu alloy subjected to different heat treatments

Precipitate behavior of Ti₂Cu particles in Ti-2.5Cu alloy subjected to different heat treatments and its effect on mechanical properties of this alloy were studied. Ti₂Cu intermetallic compounds were observed to form in two shapes: spherical particles due to decomposition of supersaturated α phase during annealing at 790 °C and acicular ones produced by aging after solution. Microstructural examinations via transmission electron microscopy (TEM) demonstrated that spherical Ti₂Cu of 0.2-0.5 μm in diameter could occur in both intra-grains and inter-grains. On the other hand, the acicular Ti₂Cu of about tens of nanometers in width and 100 nm in length nucleated in the interior of the grains. Tensile results showed that acicular particles made greater contributions to the strengthening of Ti-2.5Cu alloy than spherical ones.