Characterizing of a unique Al/Cu FGMMC fabricated via the ARB-CRB process followed by annealing

This study investigates the influence of different annealing temperatures on the microstructure and growth of the intermetallic phase in an Al/Cu functionally graded metal matrix composite (FGMMC ( produced by the accumulative roll bonding (ARB)-cold roll bonding (CRB) process. SEM images show the evolving distribution of Cu content in the composite, with the finest and thinnest Cu layer observed in the Al/20Cu region. The annealing at 400°C and 450°C for 2, 4, and 6 hours results in the formation of intermetallic layers (Al2Cu, Al4Cu9, and AlCu) with a clear progression from the Al side to the Cu side, as confirmed by SEM-EDS and TEM analysis. Increasing the annealing conditions increases the thickness of the intermetallic layers. In addition, the intermetallic layers are thicker in the FGMMC sample than in the ARB sample under the same conditions due to the additional strain during the process. The findings demonstrate that a diffusion-controlled mechanism governs the growth of the Al2Cu, Al4Cu9, and AlCu layers. The tensile test results indicate that as the Cu content increases from 20 wt.% to 80 wt.%, the ultimate tensile strength of the layers increases from 288.24 MPa to 373.66 MPa, while the elongation decreases from 8.2% to 5.3%. After annealing, however, these values decreased due to the restoration phenomenon and intermetallic formation. The fracture surface predominantly exhibits a brittle mode, especially with increasing Cu content and annealing conditions.