In situ observations of crack growth and damage progression were conducted under creep conditions for P92 and titanium aluminides inter-metallic compound. A proposed analysis of stress induced particle diffusion was applied to stress induced vacancy diffusion. Results obtained from this analysis were successfully correlated with the experimental behaviour of macroscopic damage progression and a theoretical characteristic of creep deformation was derived. It was found to be in good agreement with experimental characteristics of creep deformation. Furthermore, the experimental characteristics of creep damage progression which concern voids and micro crack formations at grain boundary were found to be well correlated with those of deformation. From these results, correlation between vacancy diffusion in nano-scale, creep damage in mezzo-scale and creep deformation in macro-scale were successfully realized.

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To solve the problem of structural safety under time-dependent fracture conditions, an algorithm of multi-scale hybrid mechanics from the nano-scale to the macro-scales is described. The paper presents an algorithm that links the physics of materials with life prediction determined by creep crack growth and addresses practical application which enables "prediction of fracture" to be developed from "the science of clarification of fracture mechanism" on the basis of the algorithm. In particular, in order to predict the fracture life of real components, the importance of the link between void mechanics caused by vacancy diffusion (micro mechanical factor), the stress tri-axiality, TF (a structural mechanical factor), and the material structure (a meso-mechanical factor) is shown in the proposed formulation for the activation energy of the thermally activated process of creep crack growth. A detailed discussion on these issues as well as on the algorithm relevant to the establishment of the law of creep crack growth life based on the multi-scale analysis is included ranging from the scale of micro damage to structural brittleness.

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