Heat treatment of binary and ternary titanium alloys

Conclusions

• 1. The addition of 0.5–14% Co effectively increases the ultimate strength of titanium at 20° (from 40 to 140 kg/mm²). In ternary Ti−Al−Co alloys the strengthening effect of cobalt is similar.

• 2. The ternary alloys retain fairly high ductility after annealing in the α+β region. Annealing in the region of α+Ti₂Co, α+α₂+β, and α₂+β+Ti₂Co greatly reduces the ductility, which is due to the presence of Ti₂Co and α₂ phases.

• 3. At elevated temperatures the strengthening effect of cobalt is retained up to 500° in both the binary and ternary alloys. At 600–650° the strength decreases considerably.

• 4. In long-term strength tests of the ternary alloys at 600° under stress of 15–20 kg/mm² the samples had a short service life.