TiAl3 is a porous material which is widely used for catalytic conversion, thermal insulation and filtration. It is characterized by low density, high specific modulus and oxidation resistance at high temperature. A line compound, it is the ideal porous material to be applied in a variety of applications.
TiAl3 phase is formed in the process of diffusion bonding. Al diffuses faster than Ti. Therefore, the density of large Al particles is greater than that of smaller particles. In this case, the increased diffusion flux leads to the formation of Kirkendall pores. These pores are located close to the Al/TiAl3 interface and will eventually concentrate over the center of the TiAl3 intermetallic layer.
The growth of TiAl3 phase is accompanied by a decrease in the grain size of the TiAl3 particles at the Ti/Al3 interface. This phenomenon was observed in the XRD pattern of sintered TiAl3 samples.
An EBSD study of MILs showed similar TiAl3 grain structure. This phenomenon is also observed in sintered discs with different particle sizes. Furthermore, the IPF Z map and OIM micrographs of the MIL demonstrate the presence of TiAl3 phase.
As the heating rate increases, the reaction temperature increases. As a result, the reaction heat becomes difficult to dissipate. When a sufficient holding time is provided, the reaction finishes completely. Then the final TiAl3 grain structure can be seen, consisting of newly-grown fine TiAl3 nuclei at the Ti/TiAl3 interface.
This process also generates micropores in the TiAl3 intermetallics. These pores are primarily attributed to solid-liquid diffusion of Ti and Al.