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In materials science, an interstitial defect is a type of point crystallographic defect where an atom of the same or of a different type, occupies an interstitial site in the crystal structure. When the atom is of the same type as those already present they are known as a self-interstitial defect .
In chemistry, the terrace ledge kink (TLK) model, which is also referred to as the terrace step kink (TSK) model, describes the thermodynamics of crystal surface formation and transformation, as well as the energetics of surface defect formation. It is based upon the idea that the energy of an atom’s position on a crystal surface is ...
where is the diffusivity of the solute atom in the host material, is the atomic volume, is the velocity of the dislocation, is the diffusion flux density, and is the solute concentration. [5] The existence of the Cottrell atmosphere and the effects of viscous drag have been proven to be important in high temperature deformation at intermediate ...
Fick's first law relates the diffusive flux to the gradient of the concentration. It postulates that the flux goes from regions of high concentration to regions of low concentration, with a magnitude that is proportional to the concentration gradient (spatial derivative), or in simplistic terms the concept that a solute will move from a region of high concentration to a region of low ...
Dislocation velocity is largely dependent upon shear stress and temperature, and can often be fit using a power law function: [14] v = A τ m {\displaystyle v=A\tau ^{m}} where A {\displaystyle A} is a material constant, τ {\displaystyle \tau } is the applied shear stress, m {\displaystyle m} is a constant that decreases with increasing ...
In crystallography, interstitial sites, holes or voids are the empty space that exists between the packing of atoms (spheres) in the crystal structure. [ citation needed ] The holes are easy to see if you try to pack circles together; no matter how close you get them or how you arrange them, you will have empty space in between.
For example, along the grain boundaries and certain crystalline defects such as dislocations there is more open space, thereby allowing for a lower activation energy for diffusion. Atomic diffusion in polycrystalline materials is therefore often modeled using an effective diffusion coefficient , which is a combination of lattice, and grain ...
The concept of diffusion is widely used in many fields, including physics (particle diffusion), chemistry, biology, sociology, economics, statistics, data science, and finance (diffusion of people, ideas, data and price values). The central idea of diffusion, however, is common to all of these: a substance or collection undergoing diffusion ...