Study on In-Situ Particle Strengthening Behavior of Intermetallic Compounds at Interface of Roll-Bonded Steel/aluminum Laminate

Roll-bonded steel-aluminum laminates have broad application prospects. Intermetallic compounds (IMCs) are precipitated phases produced at bonding interface during annealing. Generally, IMCs are assumed to reduce the bonding strength of steel–aluminum laminates. In this study, we characterize that the IMCs formed at the initial stage of annealing do not reduce the bonding strength of laminates, and they can be used as a reinforcing phase at the interface to improve the bonding strength of steel–aluminum laminates further. In-situ tensile-shear test and finite element analysis reveal the changes in interfacial fracture form and stress–strain state before and after the IMCs formation. Results show that after the formation of granular IMCs at the interface, granular IMCs can limit interface crack propagation and change the crack propagation direction during tensile shear fracture, and the maximum shear stress at the interface is transferred from the interface to the aluminum substrate. Furthermore, the fracture of laminates occurs completely on the aluminum substrate. This state is damaged when the density of the interface IMCs is extremely high. After an approximate IMCs layer is formed at the bonding interface, Kirkendall voids are observed at IMCs–aluminum interface. During tensile shear, the maximum shear stress appears at the IMCs–aluminum interface, Kirkendal voids become the crack source and propagate rapidly, and the bonding strength of the laminates decreases.