Fabrication and characterization of cold-swaged multilayered Al-Cu clad composites

Abstract

This study was focused on microstructure development and mechanical properties of three-layered Al–Cu clad composites with different stacking sequences. The composites were fabricated using cold rotary swaging (RS). To evaluate strain distribution of the individual clad composites, two variants with the overall true strain 2.2 and 2.7 were fabricated. Subsequently, heat treatments were applied to examine structure changes and a possible development of intermetallic layers.

The Cu/Al/Cu composites featured 20% higher tensile strength and microhardness after RS when compared to the Al/Cu/Al. The bending strengths were similar. Decrease of microhardness toward the swaged rods axes confirmed decrease of strain intensity. The grain size in the composites after RS was significantly refined. The structures featured bimodal grain size with a majority of grains smaller than 5 μm. A higher annealing temperature introduced higher softening. Both the heat treatment modes caused development of intermetallic layers, although their occurrence was localized for the Al/Cu/Al composite. The higher temperature resulted in an increase of intermetallic layers, but their thickness was under 2 μm. Metastable Al2Cu3 phase occurred at the lower temperature. This phase was not detected after annealing at the higher temperature. The interfacial layers consisted of AlCu3, Al2Cu and AlCu intermetallic compounds.