Mechanical properties and fracture mechanism of Fe/Cu composite sheets with Al interlayer after annealing treatment

The feasibility of preparing Fe/Cu composite sheet was achieved by introducing submillimeter thickness Al sheet as an interlayer by rolling at room temperature. The shear test of the composite sheet supported that the metallurgical bonding strength between Fe/(Al)/Cu interface was stronger than that of Cu sheet at the initial state. With further 300 or 600 °C annealing treatments, the interlayer subsequently exhibited brittle shear fracture, and the shear strength significantly dropped under the shear test. Furthermore, the tensile test pointed out that the tensile fracture mechanism changed from fracture as a whole structure to interlayer-to-layer delamination mode after annealing treatment. The microstructure and X-ray diffraction observations proved that the formation of Cu–Al intermetallic compounds (IMCs) along the interlayer resulted in brittle fracture, rather than that of Fe–Al IMCs after annealing, especially under 600 °C annealing treatment. The investigation of the effect of the rolling process and annealing treatment on the mechanical properties of the Fe/(Al)/Cu composite sheet shall provide instruction for high-quality composite metallic sheet fabrication.