The Kirkendall void formation in Al/Ti interface during solid-state reactive diffusion between Al and Ti

In the current study, the formation of Kirkendall voids in Al/Ti interface during solid-state reactive diffusion between Al and Ti was investigated. In this regards, pure Al wire (grade 1100) was deposited on commercially pure Ti surface by means of GTAW processing and the prepared samples were annealed at 625 °C for different periods of time. The achieved results indicated that, during cladding process, a continuous layer of Al3Ti intermetallic compound with average thickness of about 2 µm, can be formed in Al/Ti interface. During annealing process, both Ti and Al diffused into each other and the growth of the Al3Ti layer occurred mainly towards the Ti side. At this condition, Kirkendall voids are formed and accumulated near to Al/Al3Ti interface. These voids started to connect to one another, coalesce into large gaps and resembling a line crack at the interface. The formed crack acts as a barrier in Al/Ti diffusing couple and inhibits the growth of Al3Ti phase.