抄録
This paper presents a review of the effect of crack tip cyclic plasticity on retarded crystallographic (stage I) crack growth in metal single crystals, bicrystals, engineering polycrystals and particulate-reinforced metal matrix composites (PMMC). The cyclic plastic deformation at the tip of a crystallographic crack, is shown to be affected by tortuous crack wake, adjacent grain boundary, or by the surrounding particles in a PMMC. Evidence gathered shows that change in the crack growth direction results from the redistribution of crack tip plastic strain. Similarly, the crack growth rate deceleration is related to the reduction of the cyclic plastic strain range due to the crack tip shielding. The role of the cyclic plasticity as a driving force in the shielded crystallographic crack growth, is demonstrated. The threshold for both the short and long crack growth corresponds to a critical loading condition which produces a persistent slip band of the characteristic microstructural size.
