Titanium

Occurrence of Titanium in the earth's crust is very abundant, but extraction from the ore is very difficult. Ti  has a high melting point and a high affinity to other elements, therefore it is hard to process. The high elasticity limit causes limited machinability. Altogether Ti is quite expensive. The corrosion resistance is good, (also in aggressive environments), because of a protective layer of TiO2. Ti is biocompatible and is used in surgical applications. Pure Ti has an Alfa (HCP) crystal structure: bad cold formability (only hot forming), well weldable, good creep resistant but relatively weak. A low content of alloying elements changes the structure to a mixture of Alfa and Beta (BCC), which offer a higher strength, better formability, but lower weldability and creep resistance.  A high amount of alloying forms a structure of entirely Beta which is good cold formable. 99% of the Ti alloys are processed by forming.Ti has a high specific strength (it's light and strong) and is used in many aerospace applications.