5. Titanium alloys

5.1 Advantages of titanium

Although abundant in the earth's crust in the form of oxides, titanium is only produced as a metallic material in relatively small quantities (around 100,000 tonnes/year), as its production requires a high level of energy (around 45 kWh/kg). It's a very expensive material, which presents a somewhat exceptional position by combining a fairly low density with mechanical characteristics similar to those of steels.

Its density (ρ = 4.51) is intermediate between aluminum and steel, and its modulus of elasticity (E = 110 GPa) places it on a par with Al and Fe in terms of density: E/ρ = 25.

It has a high melting point T _f = 1,668°C and, as a result, low thermal expansion...