Metal/Ceramic Interface Fracture
Metal/ceramic interface fracture of niobium/alumina bicrystal interface had been studied at Max-Planck Institute for metal research, Stuttgart, Germany since last three decades. It was found that fracture energy of the system changes in some case by 20 times for different orientations of the bicrystal specimen. In this work a length scale bridging procedure was proposed to simulate the interface fracture of niobium/alumina bicrystal specimens. An automatic identification procedure has been proposed to identify crystal plasticity parameters involved in the material constitutive equations. Using this procedure, a large number of parameters can be identified in few minutes that used to take weeks if done manually. Effect of crystal orientation on the crack initiation energies was studied. It was found that by changing the orientation of the single crystalline material does influence the fracture energies of the bicrystal interface. The trends of these fracture energies were found to be the same as were found in the experiments. The physical phenomena involved in the variation of fracture energies for different orientations of the interface were explained quantitatively using the analyses results. A correlation was derived among macroscopic parameter (fracture energy), and micro- and nano-scale parameters, such as cohesive strength, work of adhesion and yield stress.
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