Unformatted text preview: ENGRI 111 Mechanical Response Si: Covalent bonds Metal: Metallic bonds Polymer: Covalent and van der Waals bonds Plastic deformation: material "yields" to applied stress Elastic stretching: recoverable Young's Modulus (Modulus of Elasticity), E = / Different Behaviors Metallic Bonds: Metal Ions in Sea of Electrons ATOMIC SCALE: BONDS ACT LIKE ELASTIC SPRINGS www.matsceng.ohio-state.edu Plastic Deformation www.matsceng.ohio-state.edu Knee Dislocation Atoms and Planes Close Packed Planes (Edge) Dislocation (Edge) Dislocation www.msm.cam.ac.uk Dislocations & Caterpillars Slip: deformation of material by movement of dislocations through special planes Grains and Grain Boundaries Dislocation Pile-up Additional stress needs to be applied to make dislocations move through the grain boundary Yield strength 1/d Is There a Limit? Is Nano Better?
When grains become too small mechanism changes from intragrain slip to grain boundary sliding Melting of Metal Nanoparticles Low Cost Disposable Electronics RFID Tags Flexible Displays www.nanomas.com Sintering (fusing) of nanoparticles at lower T ...
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- Fall '07
- Plasticity, Knee dislocation, ) Dislocation