What is the effect of the alloying elements of TC4 titanium alloy sheet on the transformation temperature?

What is the effect of the alloying elements of TC4 titanium alloy plate on the variable temperature? Titanium alloy is an alloy composed of titanium as the basis and other elements. Titanium has two kinds of homogeneous and heterogeneous crystals: α-titanium with dense hexagonal structure below 882℃, and β-titanium with body-centered cubic structure above 882℃. The alloying elements can be divided into three categories according to their effect on the phase transition temperature:
1, stabilize the α-phase, improve the phase transition temperature of the elements for the α-stabilizing elements, aluminum, carbon, oxygen and nitrogen, etc.. Aluminum is the main alloying element of titanium alloy, which has obvious effects on improving the strength of the alloy at room temperature and high temperature, reducing specific gravity and increasing elastic modulus.

2, stabilize the β-phase, reduce the phase transition temperature of the elements for the β-stabilizing elements, and can be divided into homocrystalline and eutectic type two. Application of titanium alloy products, the former has molybdenum, niobium, vanadium, etc.; the latter has chromium, manganese, copper, iron, silicon and so on.

3, on the phase transition temperature does not have much influence on the elements for the neutral elements, there are zirconium, tin, etc.. Oxygen, nitrogen, carbon and hydrogen are the main impurities in titanium alloys. Oxygen and nitrogen in the α-phase has a large solubility, titanium alloy has a significant strengthening effect, but the plasticity is reduced. The content of oxygen and nitrogen in titanium is usually set at 0.15-0.2% and 0.04-0.05% respectively. Hydrogen in the α-phase solubility is very small, titanium alloys dissolved in excess of hydrogen will produce hydride, so that the alloy becomes brittle. Normally, the hydrogen content in titanium alloys is controlled to be less than 0.015%. The dissolution of hydrogen in titanium is reversible and can be removed by vacuum annealing.