HIGH-TEMPERATURE FRACTURE

Deformation and fracture of materials at elevated temperatures are tim e-dependent processes. For different loading modes, cyclic or monotono us, cracks can nucleate on the free surface by localized corrosion at particles or interfaces or by cavity nucleation, growth and linkage in the interior of the material. In this short keynote paper corrosion e ffects are only discussed briefly. The main part is focused on cavity nucleation and growth. On the basis of recent measurements of cavity s ize distribution functions as a function of temperature, load and stra in in bicrystals, bimaterial interfaces and directionally solidified o xygen-dispersion strengthened alloys, cavity growth by diffusion (quas i-equilibrium and crack-like cavities) and creep is discussed. In addi tion, experimental results on the effects of cavity nucleation on grow th and the influence of cavity linkage on residual life are reported. These results are discussed from the viewpoint of predicting rupture l ife.