Dissemination of IT for the Promotion of Materials Science (DoITPoMS)



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.