Niobium/alumina bicrystal interface fracture: A theoretical interlink between local adhesion capacity and macroscopic fracture energies

In the presented work, an effort has been put to clear up the theoretical interlink between local adhesion capacity and macroscopic fracture energies by bridging different length scales, such as nano-, meso-, and macro-scale. Crystal plasticity theory along with a cohesive modelling approach has been used during this work. The influence of different cohesive law parameters (cohesive strength, work of adhesion) on the macroscopic fracture energies for three different orientations of niobium/alumina bicrystal specimens has been presented. It is found that cohesive strength has a stronger effect on macroscopic fracture energies as compared to work of adhesion. In the last part a generalized correlation among macroscopic fracture energy, cohesive strength, work of adhesion and yield stress is derived. The presented results can provide a great help to experimentalists in order to design better metal/ceramic interfaces.