The four main forms of the binary state diagram of titanium

According to I. I. Kornilov's classification, there are four main forms of phase diagrams of binary systems of titanium-rich fractions.

In the first one, both α (densely arranged hexagonal lattice) and β (body-centered cubic lattice) are continuous solid solution systems (Fig. a). There are only two such binary systems, the Ti-Zr and Ti-Hf systems. The reason why titanium forms a and β continuous solid solution with zirconium and hafnium is that titanium, zirconium, and hafnium are elements of the same group in the periodic table, and their atoms have the same outer electronic structure, the same type of lattice, and similar atomic radii. It can be envisioned that the ternary system of Ti-Zr-Hf will also form a ternary continuous solid solution.

In the second type, β is a continuous solid solution and α is a finite solid solution system (Fig. b). There are four such binary systems, which are Ti-Mo, Ti-V, Ti-Nb and Ti-Ta. As Mo, V, Nb, Ta, these four metals have only one crystal type, that is, body-centered cubic lattice, so they only have the same crystal type with β β-Ti form a continuous solid solution, and with the dense rows of hexagonal lattice of aTi on the formation of a limited solid solution, when titanium and aluminum, vanadium, niobium, tantalum composed of multiple alloys, will also form a variety of β β is a continuous solid solution and a for a limited solid solution.

Thirdly, in the solid state, inclusion reactions and the formation of one or several metal compounds system (Fig. c). The binary systems that form this phase diagram are Ti-Al, Ti-Sn, Ti-Ce, Ti-B, Ti-C, and so on. The first three systems have a wide α solid solution interval, which is important in heat-resistant titanium alloys.

The fourth, solid state eutectic reaction and the formation of certain compounds system (Figure d). Examples of Ti-Sc, Ti-Cr, Ti-W, Ti-U, Ti-Mn, Ti-Fe, Ti-Co, Ti-Ni, TiCu, Ti-Pd, Ti-Pb binary system.

In the periodic table of more than 100 elements, can form a binary system with titanium phase diagram there are more than 70, there are about 50 ~ 60 research data.