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METHOD:PUBLISH
BEGIN:VEVENT
DTSTAMP:20260825T180540Z
UID:https://www.mpie.de/events/10304/3755656
DTSTART:20170704T130000Z
DTEND:20170704T140000Z
CLASS:PUBLIC
CREATED:20170614T122934Z
DESCRIPTION: Size effects are a key ingredient to control and improve the m
 echanical behaviour of metallic microstructures and miniaturized component
 s. The analysis of size effects in metals has received continuous attentio
 n in the past two decades\, both experimentally and numerically. This lect
 ure focuses on the role of grain and phase boundaries in restricting dislo
 cation motion\, giving rise to size effects. Some essential features of a 
 thermodynamically consistent model for a grain boundary are presented\, wh
 ich accounts for the grain boundary energy and defect structure and evolut
 ion. The role of a phase boundary is investigated with a dislocation trans
 port driven crystal plasticity model\, revealing the explicit role of the 
 plastic phase contrast and phase boundary resistance. Interesting size eff
 ects are thereby recovered. Size effects can also be eliminated or inhibit
 ed by other microstructural mechanisms. Two cases are addressed to illustr
 ate this. The first case reveals the role of dislocation climb and its eff
 ectiveness in dissolving dislocation pile-ups. The second case concerns a 
 very thin austenitic film in martensite\, whereby the particular structure
  of the phase and its interface give rise to preferential sliding mechanis
 ms that circumvent the common dislocation driven size effects.This lecture
  addresses the strengthening role of internal boundaries\, constituting a 
 major con- tribution to size effects in metals. It is shown that besides d
 islocation pile-ups\, other mechanisms may be essential. For grain boundar
 ies\, the defect absorption and redistribution matters. For phase boundari
 es\, phase contrast in dislocation transport alone already contributes to 
 size effects. Moreover\, dislocation-pile ups can be dissolved through cli
 mb at higher temperatures or circum- vented by other particular micromecha
 nisms. This analysis effectively illustrates that predicting size effects 
 in metals quantitatively remains a major challenge. References [1] van Bee
 rs P.R.M.\, Kouznetsova V.G.\, Geers M.G.D.: Defect redistribution within 
 a continuum grain boundary plasticity model. J. Mech. Phys. Solids 83:243-
 262\, 2015.[2] Dogge M.M.W.\, Peerlings R.H.J.\, Geers M.G.D.: Interface m
 odeling in continuum dislocation transport. Me- chanics of Materials. 88:3
 0-43\, 2015.[3] Geers M.G.D.\, Cottura M.\, Appolaire B.\, Busso E.P.\, Fo
 rest S.\,Villani A.: Coupled glide-climb diffusion- enhanced crystal plast
 icity. J. Mech. Phys. Solids. 70:136-153\, 2014.[4] Maresca F.\, Kouznetso
 va V.G.\, Geers M.G.D.: Subgrain lath martensite mechanics: a numerical-ex
 perimental analysis. J. Mech. Phys. Solids. 73:69-83\, 2014.[5] Maresca F.
 \, Kouznetsova V.G.\, Geers M.G.D.: Deformation behaviour of lath martensi
 te in multi-phase steels. Scripta Materialia 110:74-77\, 2016.[6] Maresca 
 F.\, Kouznetsova V.G.\, Geers M.G.D.: Predictive modeling of interfacial d
 amage in substructured steels: application to martensitic microstructures.
  Mod. Sim. Mat. Sc. Engng. 24(2):025006\, 2016.[7] Du C.\, Hoefnagels J.P.
 M\, Vaes R.\, Geers M.G.D.: Block and sub-block boundary strengthening in 
 lath marten- site\, Scripta Materialia\,116:117-121\, 2016.[8] Du C.\, Hoe
 fnagels J.P.M\, Vaes R.\, Geers M.G.D.: Plasticity of lath martensite by s
 liding of substructure boundaries\, Scripta Materialia 120:37-40\, 2016.\n
 Speaker: Prof. Marc Geers
LAST-MODIFIED:20180214T115425Z
LOCATION:Max-Planck-Institut für Eisenforschung GmbH\, Room: Seminar Room 
 1
ORGANIZER;CN=Prof. Gerhard Dehm   :mailto:stein@mpie.de
SUMMARY:MPIE Colloquium:  Size Effects in Metals: On the Role of Internal B
 oundaries across the Scales 
URL;VALUE=URI:https://www.mpie.de/events/10304/3755656
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