Dislocation Energetics
AimsBefore you startIntroductionMaking a dislocationJoin the crystals to form the dislocationDislocation widthForm of the displacementChange in the misfit energy of a dislocation as it movesPeierls energyWhat is the Peierls stress? Determining the Peierls stressLattice resistanceUses and limitations of the atomistic modelSummaryQuestionsGoing furtherTLP creditsTLP contentsShow all contentViewing and downloading resourcesAbout the TLPsTerms of useFeedbackCredits Print this page
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Summary
There are two types of energy associated with a dislocation
- In-plane energy – decreases as dislocation width increases, so acts to spread the misfit strain over a larger region
- Misalignment energy – increases as the dislocation width increases, so acts to localise the misfit strains
- The dislocation width will be the value for which the sum of the two types of energy is a minimum
- w/b is strongly dependent on d/b, where b is the atom spacing parallel to the slip plane and d normal to it.
- Changes in misfit energy are the primary obstacle to dislocation motion.
- Using the atomistic model with a moving origin allows us to estimate the energy as the dislocation moves, hence we can determine the Peierls energy and the Peierls stress.
- Peierls stress increases exponentially as the dislocation width w/b decreases.