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SUMMARY:A probabilistic explanation for the size-effect in crystal plastic
 ity
DTSTART:20141104T131500
DTEND:20141104T141500
DTSTAMP:20260407T064452Z
UID:6430552be52c8433159e0d4e6b2aa5a793d9e2507b638d264f3d838f
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr. P. Derlet\, Condensed Matter Theory Group\, Paul Scherrer 
 Institut\, Switzerland\nBio : In 1995 I obtained a PhD in theoretical phys
 ics at Monash University\, Australia\, in Quantum Field Theory. After trai
 ning as a school teacher\, I did a post-doc at NTNU\, Trondheim\, Norway o
 n the atomistic modeling of series 6000 Al-Si-Mg and AL-Li alloys. I then 
 moved to Switzerland and worked as a staff scientist at PSI in the group o
 f Helena Van Swygenhoven doing atomistic simulation of nanocrystalline met
 als. Since 2008\, I have been in the Condensed Matter Theory group where I
  specialize in magnetism in defect dominated materials and the fundamental
  aspects of plasticity in both crystalline and amorphous solids.\nIn this 
 talk\, the well-known power-law relation between strength and sample size\
 , 1/d^n\, is discussed in terms of the universal properties of a dislocati
 on network and the leading order stress dependence of an underlying critic
 al stress distribution. This approach gives an explicit expression for the
  the size effect exponent\, n=(tau+1)/(alpha+1)\, where alpha is the leadi
 ng order algebraic exponent of the low-stress regime of the critical stres
 s distribution and tau is the scaling exponent for intermittent plastic st
 rain activity. This quite general derivation supports the experimental obs
 ervation that the size effect paradigm is applicable to a wide range of ma
 terials\, differing in crystal structure\, internal microstructure and ext
 ernal sample geometry\, and also motivates a new class of deformation expe
 riments investigating strength in terms of both material size and shape.
LOCATION:CM 1 4 https://plan.epfl.ch/?room==CM%201%204
STATUS:CONFIRMED
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