Titanium alloy is an alloy based on titanium and composed of other elements. There are two kinds of isocrystals of titanium: titanium is an isomer with a melting point of 1668℃ and a close-packed hexagonal lattice structure below 882℃, which is called α-titanium; At 882℃ above the body - centered cubic character structure, known as beta - titanium. By making use of the different characteristics of the two structures of titanium alloys, appropriate alloying elements are added to make the phase transition temperature and component content of the alloys change gradually and a titanium alloy of different microstructure is obtained.
Titanium alloy elements can be classified into three categories according to their effects on phase transition temperature:
① The elements that stabilize the α phase and increase the phase transition temperature are the α stable elements, including aluminum, carbon, oxygen and nitrogen. Aluminum is the main alloying element of titanium alloy, which has obvious effect on improving the strength of alloy at room temperature and high temperature, reducing specific gravity and increasing elastic modulus.
② The elements that stabilize β phase and reduce the transformation temperature are β stable elements, which can be divided into two types: isomorphic and eutectoid. The former has molybdenum, niobium, vanadium and so on; The latter has chromium, manganese, copper, iron, silicon and so on.
③ The elements that have little effect on the temperature of phase transformation are neutral elements, such as zirconium and tin.
