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SUMMARY:Beyond slip circle constructions: the cohesion limit of a polycrys
 tal - Prof. L.M. Brown\, SMF Group\, Cavendish Laboratory
DTSTART:20071122T160000Z
DTEND:20071122T170000Z
UID:TALK8405@talks.cam.ac.uk
CONTACT:Stephen Walley
DESCRIPTION:Slip circle constructions produce a simple semi-quantitative f
 ramework for the analysis of indentation plasticity for wedge-shaped and c
 ylindrical indenters. A method is suggested to relate these patterns bette
 r to slip systems in real crystals. Basically\, combinations of slip syste
 ms which produce rotations and not symmetrical strains can be used to desc
 ribe crystallographic slip leading to the pile-up of matter around the ind
 enter. Such combinations have been ignored in the past. They lead also to 
 a Hall-Petch law in polycrystals. The residual stress at grain boundaries 
 provides a force driving intergranular fracture. The same reasoning provid
 es a simple explanation for the lack of adhesion between sliding blocks in
  contact\, even when plastic junctions are formed between them\, and Amont
 on's law is obeyed.
LOCATION:Mott Seminar Room\, Cavendish Laboratory\, Department of Physics
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