Dislocations dislocation energy

When metals are deformed plastically at room temperature the dislocation density goes up enormously (to =10 m ). Each dislocation has a strain energy of about Gb /2 per unit length and the total dislocation strain energy in a cubic metre of deformed metal is about 2 MJ, equiva-lent to 15 J mol k When cold worked metals are heated to about 0.6T new strain-free grains nucleate and grow to consume all the cold-worked metal. This is called - for obvious reasons - recrystallisation. Metals are much softer when they have been recrystallised (or "annealed"). And provided metals are annealed often enough they can be deformed almost indefinitely. 

An elastic continuum model, which takes into account the energy of bending, the dislocation energy, and the surface energy, was used as a first approximation to describe the mechanical properties of multilayer cage structures (94). A first-order phase transition from an evenly curved (quasi-spherical) structure into a... 

Another quantity of interest is the velocity dependence of the energy of the dislocation. The energy density in the material around the dislocation, w, is the sum of the elastic strain-energy density and the kinetic-energy density,... 

Strictly speaking, we should include a core energy term in the expression for the dislocation energy, but this term is negligible in the limit so it can be omitted for the purposes of this discussion. 

Because of the large effective mass of a dislocation, the shape of the lattice potential often is not important which allows the lattice potential to be approximated by rectangular potential barriers. For modest shear stress levels, where the dislocation energy is less than the lattice potential, c < U, the probability that a dislocation of energy z will tunnel through a rectangular potential barrier of height U is [19]... 

Dislocation Energies Calculated for Sodium Chloride Assuming a Burgers Vector of Unit Strength along <110> and an Outer Badius (R) of 10 ... 

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