Micro-/nano-scale interface structure and mechanical characteristics of the Al/Ti composite bar produced by a novel continuously-extruded technique

Abstract

In this work, a novel extrusion die for embedding the continuous Ti wire into the aluminum alloy is developed, and the extruded composite bar is obtained. The multi-scale interface structure, elemental diffusion, and mechanical characteristics are investigated by different material characterization methods. The three-dimensional (3D) amorphous regions are produced on the well-bonded Al/Ti interface. The formation of a nanocrystalline Al layer is accompanied by the precipitation of Mg-/Si-enriched clusters. With an increase in the annealing time, the average grain size of TiAl3 increases, while the dislocation density of the TiAl3 layer decreases. A nanoscale TiAl3 monolayer is exhibited between the Al/TiAl3 and Kirkendall interfaces, whereas two types of nanoscale TiAl3 grains are detected on the Ti/TiAl3 interface. The Si-enriched clusters are aggregated at the Ti/TiAl3 interface, generating a nanoscale layer. Local inhibition behaviors of large-sized Mg-enriched clusters on the growth of TiAl3 are observed at the Al/TiAl3 interface after annealing for 48 h. Not only are massive misfit dislocations and distorted lattices detected on the 3D interface, but also locally ordered transition zones are noticed. The extruded composite bar exhibits a superior strength-ductility balance, which provides a new strategy for the development of aluminum profiles.

Keywords

• Metal-matrix composites
• Interface
• Micro-mechanics
• Microstructural analysis
• Extrusion