Microstructural characterization and mechanical performance of an AA2024 aluminium alloy — Pure copper joint obtained by linear friction welding

• The microstructure of a dissimilar AA2024 - Cu linear friction joint is investigated at a fine scale.
• A phenomenological mechanism of material flow is proposed.
• Al2Cu, AlCu, Al2Cu3, Al4Cu9 as well as two metastable phases are identified.
• The interfacial zone presents ideal crystallographic shear texture components.
• The intermetallic compounds are harmful for the tensile properties of the joint.

The present work deals with the microstructural and mechanical characterization of an AA2024 – pure Cu linear friction weld. A thorough study of the microstructural features in close contact with the interface led to propose a phenomenological mechanism of material flow. The interface is covered by a discontinuous layer of intermetallic compounds. Al2Cu, AlCu, Al2Cu3 and more particularly Al4Cu9 were detected. Two metastable phases, i.e. an Al3Cu2 compound and an out-of-equilibrium Al solid solution containing 13 at.% Cu, were also identified at the interface and on the Al side, respectively. In accordance with the applied strain state during welding, ideal shear texture components were formed on both sides of the joint. Due to the formation of large intermetallic compounds, the mechanical resistance of the joint remains to be improved.

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