Thermodynamic aspects of Cottrell atmospheres

• Published in: Philosophical magazine (Abingdon, England) Vol. 93; no. 28-30; pp. 3741 - 3746
• Main Author: Cahn, J.W.
• Format: Journal Article
• Language: English
• Published: Abingdon Taylor & Francis 30.09.2013
• Subjects: Alloys; Applied sciences; Atmospheres; Burgers vector; Condensed matter: structure, mechanical and thermal properties; Dislocations; Edge dislocations; elasticity; Elasticity. Plasticity; Equations of state, phase equilibria, and phase transitions; Exact sciences and technology; grain boundaries; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Open systems; Physics; Solubility, segregation, and mixing; phase separation; Stress concentration; Stresses; Elastic constant; Stress distribution; Experimental design; Segregation; Open systems; Elasticity; Edge dislocation; Burgers vector; Concentration distribution
• ISSN: 1478-6435; 1478-6443
• DOI: 10.1080/14786435.2013.793853

Using open system elastic constants, we can convert any of the many existing solved small-strain problems of stress fields of dislocation configurations to what the stresses and solute distribution equilibrium would be in alloys. We confine ourselves to small strain linear isotropic elasticity in which the solute atoms are centres of pure dilation and compute the inhomogeneous compositional distributions that are called Cottrell atmospheres, as well as the energy changes due to the segregation. We correct the misconception in the literature that the solute distribution does not affect the stress field of the dislocation and show that the atmosphere around an edge dislocation acts like an edge dislocation with a Burgers vector of opposite sign.