1. News

TiAl3 Type

A TiAl3 type is an intermetallic phase that grows in a Ti/Al trilayer system. This phase is characterized by a grey color and a coarse globular structure. The growth of this phase is governed by a diffusion-controlled mechanism. It also exhibits unequal involvement in isolobal bonding.

The growth of this phase is influenced by the chemical composition of the Ti/Al intermetallic layer. In particular, the Al density is higher than that of the Ti layer. These differences are determined by the diffusion-controlled mechanism and the reaction-controlled mechanism.

During the formation of the TiAl3 intermetallic phase, the Ti atoms interdiffuse into the Al matrix. The resulting TiAl3 grains are distributed along the thickness of the intermetallic layer. They tend to move towards the Al side.

The growth rate of the TiAl3 grains is accelerated at the Ti/TiAl3 interface. The nuclei at this interface are nano-sized. Their dominant nucleation is shown in the figure.

The TiAl3 type consists of one electron per Ti atom short of the ideal number of 18 electron configurations. However, the EF of this structure is very close to the DOS minimum of the pseudogap. This is an electronic precision that confirms the prediction of the 18-n rule.

Since the ZrAl3 structure has an electron count of 13 electrons/Zr atom, it should be energy neutral for T = Zr. However, EF of the structure is higher than that of the TiAl3 type. This is because the Al atoms at the Al2b site have a net positive atomic CP, whereas those at the Al4d site have a net negative atomic CP.

Inquiry us