Optimisation of interface formation by shear inclination: Example of aluminium-copper hybrid produced by ECAP with back-pressure

Highlights: • Detailed crystallographic analysis of intermetallic compounds on the Al-Cu interface after hot deformation was performed. • Very rarely reported orthorhombic ζ₂-Al₃Cu_4-δ phase was identified as one of the compounds. • The optimum thickness of the interface for high mechanical stability was found to be in the range of 3-5 μm. • The interplay between the diffusion and recrystallization processes governs the formation of the Al-Cu intermixing zone. Hybrid materials present a convenient way of combining properties of more than one material in one product. However, there are problems associated with such manufacturing, particularly, in relation to the properties of the interface between components. Intermetallic compounds can potentially form in this area, whose size and composition can have a profound effect on mechanical properties of the product. In this work, we investigate the effect of temperature, mutual arrangement and hydrostatic pressure on the quality of the interface between Al and Cu parts, processed simultaneously by severe plastic deformation. We show that three intermetallic compounds - θ-Al₂Cu, ζ₂-Al₃Cu_4-δ and γ₁-Al₄Cu₉ - form on the interface. It is shown that the formation of these phases on the interface between aluminium and copper highly depends on the combination of diffusion and recrystallization process.