Heterostructure‐Specific Toughening Mechanisms in Metallic Laminates

Heterostructured materials, including laminated metallic composites, have the potential to provide efficient solutions for cyclically stressed components with damage‐tolerant designs. Metallic laminates can be manufactured cost‐effectively using the accumulative roll‐bonding process, are fully recyclable and can offer significantly superior resistance to crack growth compared to their monolithic counterparts. The present study focuses on the analysis of heterostructure‐specific toughening mechanisms in heterogeneous Al/Al‐ and Al/Cu‐laminates. In the case of the Al/Cu‐laminates, the observed increase in damage tolerance is attributed to their interfacial structure, resulting in the emergence of interface structure related crack deflection mechanisms at the interfaces. For heterogeneous Al–Al laminates, the improvement in fracture resistance at high cyclic loading is attributed to material inhomogeneity effects, resulting in the emergence of strain state‐related crack bifurcation and stress state‐related crack deflection mechanisms in the vicinity of interfaces. Strong correlation is found between the results of the surface crack growth analysis method and the method characterizing 3D crack growth within the specimen volume of metallic laminates. The results presented in this study demonstrate how different aspects regarding the heterostructure of metallic laminates can be specifically tailored to achieve improved fracture resistance for damage‐tolerant designs of cyclically stressed components.