About the Role of Interfaces on the Fatigue Crack Propagation in Laminated Metallic Composites

Abstract

The influence of gradients in hardness and elastic properties at interfaces of dissimilar materials in laminated metallic composites (LMCs) on fatigue crack propagation is investigated experimentally for three different LMC systems: Al/Al-LMCs with dissimilar yield stress and Al/Steel-LMCs as well as Al/Ti/Steel-LMCs with dissimilar yield stress and Young’s modulus, respectively. The damage tolerant fatigue behavior in Al/Al-LMCs with an alternating layer structure is enhanced significantly compared to constituent monolithic materials. The prevalent toughening mechanisms at the interfaces are identified by microscopical methods and synchrotron X-ray computed tomography. For the soft/hard transition, crack deflection mechanisms at the vicinity of the interface are observed, whereas crack bifurcation mechanisms can be seen for the hard/soft transition. The crack propagation in Al/Steel-LMCs was studied conducting in-situ scanning electron microscope (SEM) experiments in the respective low cycle fatigue (LCF) and high cycle fatigue (HCF) regimes of the laminate. The enhanced resistance against crack propagation in the LCF regime is attributed to the prevalent stress redistribution, crack deflection, and crack bridging mechanisms. The fatigue properties of different Al/Ti/Steel-LMC systems show the potential of LMCs in terms of an appropriate selection of constituents in combination with an optimized architecture. The results are also discussed under the aspect of tailored lightweight applications subjected to cyclic loading.

Structure, Mechanical and Physical Properties of Cu/Al–10% La Composite Produced by Rotary Forging

“…Cracks nucleated in a higher strength copper shell slow down or stop completely in a more ductile aluminum rod. In addition, the copper/aluminum alloy interface itself is a barrier to crack propagation [23].…”

Quantifying Co-Deformation Effects in Metallic Laminates by Loading–Unloading–Reloading Tensile Tests

“…Based on synergistic interaction and coupling effects between the heterogeneous zones, improved mechanical and functional trade-off properties have been reported, such as strength-ductility [6,7] and magnetizationcoercivity [8,9]. Depending on the morphology of the heterogeneous zones, heterostructured materials can be divided into different categories, including harmonic [10][11][12], gradient [13,14], bimodal [15,16] or laminated materials [17][18][19]. In heterostructured materials, the heterogeneous zones can consist, for instance, of mechanically soft and hard zones separated by boundaries such as grain boundaries or interfaces.…”

A new method for microscale cyclic crack growth characterization from notched microcantilevers and application to single crystalline tungsten and a metallic glass

“…Alternating start-up and shut-down cycles lead to low cycle fatigue (LCF), small vibrations sum up over long time for high cycle fatigue (HCF), thermal cycling leads to thermo mechanical fatigue, etc. Consequently there is a need for different techniques to characterize fatigue under different loadings, environments and scales [1][2][3][4][5]. Microsamples are so far only seldom used to determine the fatigue failure and crack growth behavior.…”