Contrasting the nature of fatigue-crack propagation in ductile and brittle materials

摘要

The mechanisms of fatigue-crack propagation in ceramics and intermetallic materials are examined through a comparison of cyclic crack-growth behavior in ductile and brittle materials. This is achieved by considering crack growth as a mutual competition between intrinsic mechanisms of crack advance ahead of the crack tip, which promote crack growth, and extrinsic mechanisms of crack4ip shielding behind the tip, which impede it. The widely differing nature of these mechanisms and their specific dependence upon the alternating and maximum driving forces (e.g. △K and K{sub}max) provide a useful distinction of the process of fatigue-crack propagation in these different classes of materials.