Dislocations emitted from a crack tip in silicon single crystals have been investigated using a high voltage electron microscopy (HVEM). The influence of those crack tip dislocations on the fracture toughness has been discussed based on the 3-D stress analysis of crack-dislocation interaction. Pure screw dislocations were introduced not only ahead of a crack tip but also behind the tip. The dislocations ahead of the crack tip have the sign of Burgers vectors opposite to that of the dislocations behind the tip. These configurations of crack tip dislocations are understood by dislocation loop expansion from sources near the crack tip. The contribution to the fracture toughness by those crack tip dislocations was calculated, and it was found that 70-90% increase in the fracture toughness was caused by a dislocation configuration corresponding to that observed in the early stage of dislocation emission from a crack tip.
|Number of pages||8|
|Journal||Nippon Kikai Gakkai Ronbunshu, A Hen/Transactions of the Japan Society of Mechanical Engineers, Part A|
|Publication status||Published - Nov 2002|
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Mechanics of Materials
- Mechanical Engineering