Is titanium alloy a heavy metal? Is it poisonous?

The content of titanium alloy encyclopedia comes from: Titanium alloy Titanium alloy is an alloy composed of other elements added on the basis of titanium. Titanium has two isomorphous crystals: titanium is an isomer, with a melting point of 1720 ° C. It is a close-packed hexagonal lattice structure below 882 ° C, called α titanium; at 882 ° C, it is a body-centered cubic character. Structure, called beta titanium. Using the different characteristics of the above two structures of titanium, adding appropriate alloying elements, gradually changing the phase transition temperature and phase content to obtain titanium alloys with different microstructures.

The alloying elements titanium can be divided into three categories according to their influence on the phase transition temperature:

1 The element which stabilizes the α phase and raises the phase transition temperature is α stable element, such as aluminum, carbon, oxygen and nitrogen. Among them, aluminum is the main alloying element of titanium alloy, which has obvious effects on improving the normal temperature and high temperature strength of the alloy, reducing the specific gravity and increasing the elastic modulus.

2 The element which stabilizes the β phase and lowers the phase transition temperature is β stable element, and can be divided into two types: isomorphous form and eutectoid form. The former has molybdenum, niobium, vanadium, etc.; the latter has chromium, manganese, copper, iron, silicon and the like.

3 The elements that have little effect on the phase transition temperature are neutral elements, such as zirconium and tin.

Oxygen, nitrogen, carbon and hydrogen are the main impurities of titanium alloys. Oxygen and nitrogen have a large solubility in the α phase, and have a significant strengthening effect on the titanium alloy, but the plasticity is lowered. The content of oxygen and nitrogen in the titanium is usually specified to be 0.15-0.2% and 0.04-0.05%, respectively. Hydrogen has a low solubility in the alpha phase, and excessive hydrogen is dissolved in the titanium alloy to produce a hydride which makes the alloy brittle. Usually, the hydrogen content in the titanium alloy is controlled to be 0.015% or less. The dissolution of hydrogen in titanium is reversible and can be removed by vacuum annealing. However, the contact is not toxic.