Atomic diffusion mechanism and interface nanomechanics in the Al/Ti composite structures

Abstract

In this work, Al/Ti composite structures are obtained by isothermal compression at 550 °C and then annealed at 500–650 °C, respectively. The microstructure, elemental diffusion behavior , bonding characteristic and nanomechanics at the Al/Ti interface are systematically investigated by different material characterization methods. A nanoscale Al–Ti solid solution is formed at the contact interface between AA6063 and Ti–6Al–4V sheet, and TiAl 3 is generated after annealing. Si-enriched clusters at the Ti/TiAl 3 interface and Mg-enriched clusters at the Al/TiAl 3 interface are observed, which retards the growth of the TiAl 3 layer. With an increase in the annealing temperature, the average thickness of the TiAl 3 layer dramatically increases and the enrichment of Si and Mg decreases. Ordered TiAl 3 is gradually formed through the atomic rearrangement in the Ti–Al–Si–V structures at the three-dimensional Ti/TiAl 3 interface, accompanied by the transformation of an order–disorder–order structure. The nanomechanics at the interface is closely related to the annealing temperature, elemental diffusion and microstructure characteristic, which is also discussed. • Si-enriched and Mg-enriched clusters are observed at the Al/Ti interface, which retards the growth of TiAl 3 . • With an increase in temperature, the thickness of the TiAl 3 layer increases and the enrichment of Si and Mg decreases. • TiAl 3 is formed by the atomic rearrangement in Ti–Al–Si–V structures and the transformation of a disorder–order structure. • Differences of the nanomechanics at the interface cause the deformation incompatibility and interfacial debonding.