Dislocation dynamics and brittle-to-ductile transitions

摘要: Abstract The validity of different types models for crack-dislocation interactions and their effect on fracture is discussed. brittle-to-ductile transition (BDT) in precracked silicon sapphire can be described by a two-stage dynamic model based dislocation motion to around the crack tip. In germanium, where stress-temperature-velocity relations test materials are known, allows accurate prediction temperature. Computer simulations development near-crack tip arrays then shape BDT given pre-existing arrangements crystals; we have performed experiments confirm these predictions. sapphire, data not available, allowed velocities from tests. These predictions were checked measuring found close fit experiment. We also studied brittle-ductile semibrittle (b.c.c. metals oxides), dislocations appear control behaviour via slow, stable growth. molybdenum growth relatively small extent our predicts stress-temperature curve good accuracy.