IUTAM Symposium on Mechanical Behavior and Micro-Mechanics of Nanostructured Materials : proceedings of the IUTAM symposium held in Beijing, China, June 27-30, 2005

In order to model the effects of grain boundaries in nanocrystalline materials we have coupled a crystal-plasticity model for the grain interiors with a new elastic-plastic grainboundary interface model which accounts for both reversible elastic, as well irreversible inelastic sliding-separation deformations at the grain boundaries prior to failure. We have used this new computational capability to study the deformation and fracture response of nanocrystalline nickel. The results from the simulations capture the macroscopic experimentallyobserved tensile stress-strain curves, and the dominant microstructural inelastic deformation and fracture mechanisms in this material. The macroscopically-observed nonlinearity in the stress-strain response is mainly due to the inelastic response of the grain boundaries. Plastic deformation in the interior of the grains prior to the formation of grain-boundary cracks was rarely observed. The stress concentrations at the tips of the distributed grain-boundary cracks, and at grain-boundary triple junctions, cause a limited amount of plastic deformation in the high-strength grain interiors. The competition of grain-boundary deformation with that in the grain interiors determines the observed macroscopic stress-strain response, and the overall ductility. In nanocrystalline nickel, the high yield strength of the grain interiors and relatively weaker grain-boundary interfaces account for the low ductility of this material in tension. Front Matter....Pages i-xvi Front Matter....Pages 1-1 Mesoscopic Modeling of the Deformation and Fracture of Nanocrystalline Metals....Pages 3-10 Dislocation-Assisted Grain Growth in Nanocrystalline Copper under Large Deformation....Pages 11-18 Microstructure and Tensile Strength of Cu with Nano-Scale Twins....Pages 19-24 Microstructural Evolution in Crystalline Metal Induced by Plastic Deformation....Pages 25-35 Front Matter....Pages 37-37 The Origin of Superhardness in Nanocomposite Coatings: Analysis of Nanoindentation and Scratch Tests....Pages 39-49 Micromechanics of Nanocomposites with Interface Energy Effect....Pages 51-59 Measurements and Simulations of Interface Behavior in Metal Thin Film Peeling Along Ceramic Substrate....Pages 61-70 Micro-Cantilevers for Thin Films: Young’s Modulus....Pages 71-83 Front Matter....Pages 85-85 Bio-Inspired Mechanics of Bone-Like Hierarchical Materials....Pages 87-94 Force Unfolding Single RNAs: From Equilibrium to Far-From Equilibrium....Pages 95-104 Modelling the Thermal Conductivity of Nanofluids....Pages 105-118 Front Matter....Pages 119-119 A Comparison of Different Interatomic Potentials: Radius Effect of Single Wall Carbon Nanotubes....Pages 121-134 Shape Memory Effect and Pseudoelasticity in Cu Nanowires....Pages 135-144 Instabilities of Carbon Nanotubes Studied Using a Hybrid Atom/Continuum Approach....Pages 145-152 Shallow and Deep Nanoindentation on W/NbN Nanolayers....Pages 153-159 Front Matter....Pages 161-161 Cluster Statistical Thermodynamics (CST) — To Efficiently Calculate Quasi-Static Deformation at Finite Temperature Based on Molecular Potential....Pages 163-170 On the Size of the Representative Volume Element for Isotropic Elastic Polycrystalline Copper....Pages 171-180 Atomistic Corroboration of a Multiscale Approach for the Analysis of Dislocation Nucleation at a Surface Step....Pages 181-189 Indenter Tip Radius and Micro-Indentation Hardness....Pages 191-199 Front Matter....Pages 201-201 The Phase Angle of an Interface Crack Induced by Indentation Delamination with Buckling....Pages 203-209 Front Matter....Pages 201-201 Microscopic Shape Memory and Superelastic Effects and Their Novel Tribological Applications....Pages 211-217 Dynamics of Self-Organized Epitaxial Island Formation under Controlled Annealing....Pages 219-228 Studying Visco-Plasticity of Amorphous Polymers by Indentation Tests....Pages 229-238 Phase Transitions of Carbon Materials under High Pressure....Pages 239-249 Back Matter....Pages 251-261 Recently, we have seen that nano-structured materials demonstrate remarkable - vantagesoverconventionalones, particularlyinmechanicalbehaviors. Thiswill have a great impact on new technologyand engineeringin the new millennium. In acco- ance with this need, IUTAM decided to hold a symposium to discuss the prospect of the wonderful mechanical behaviors of nanostructured materials and their relevant micro-mechanics, to encourage the mechanics community to explore the frontier of scienceandtechnology. Theaimofthesymposiumwasto providesucha forumto all expertsinbothmechanicsandmaterialsciencesworldwide, tohaveanopportunityto exchange their research achievements and views in understanding these mechanical behaviors, exploring their applications, as well as enhancing their property designs of nanostrucutred materials. The IUTAM Symposium on Mechanical Behavior and Micro-mechanics of Nanostructured Materials was held successfully in Beijing, China, June 27-30, 2005. Thirty participants with different research backgrounds including mechanics, materials sciences, physics, etc. from Australia, France, Germany, Japan, Singapore, UK and USA and China presented their contributions on various aspects closely - lated to the subjects, displaying wide research direction and progress This volume contains the proceedings of the IUTAM Symposium on Mechanical Behavior and Micro-mechanics of Nanostructured Materials, held in Beijing on June 27-30, 2005. The proceedings consist of approximately 30 presentations. Nano-scale, micro-scale, theoretical, experimental and numerical aspects of the subjects are covered. A wide scope of research and progress are displayed. This is the first work in print on this particular subject. Consisting of approximately 30 presentations from distinguished scholars, this text contains the proceedings of the 'IUTAM Symposium on Mechanical Behavior and Micro-Mechanisms of Nanostructured Materials', held in Bejing, China, during June 2005