摘要
In situ tensile test of brass foil specimens in TEM showed that many dislocations were emitted from a loaded crack tip, and a dislocation free zone (DFZ) was formed under the condition of constant displacement. The DFZ is an elastic zone, where the stress may equal to the cohesive strength sigma //t//h when the applied stress is high enough. As a result, nano-cracks would initiate discontinuously in the DFZ or, sometimes, at a blunted-crack tip. As soon as the nano-crack nucleated, it quickly blunts into a void, which results in ductile fracture. (Edited author abstract) 10 Refs.
In situ tensile test of brass foil specimens in TEM showed that many dislocations were emitted from a loaded crack tip, and a dislocation free zone (DFZ) was formed under the condition of constant displacement. The DFZ is an elastic zone, where the stress may equal to the cohesive strength sigma //t//h when the applied stress is high enough. As a result, nano-cracks would initiate discontinuously in the DFZ or, sometimes, at a blunted-crack tip. As soon as the nano-crack nucleated, it quickly blunts into a void, which results in ductile fracture. (Edited author abstract) 10 Refs.
