Reprise: partial chemical strain dislocations and their role in pinning dislocations to their atmospheres

• Published in: Philosophical magazine (Abingdon, England) Vol. 94; no. 27; pp. 3170 - 3176
• Main Author: Cahn, J.W.
• Format: Journal Article
• Language: English
• Published: Abingdon Taylor & Francis 22.09.2014
• Subjects: alloys; Atmospheres; Condensed matter: structure, mechanical and thermal properties; Cottrell atmosphere; Dislocation pinning; Dislocations; Elasticity, elastic constants; equilibrium; Exact sciences and technology; hardening; inhomogeneous strain; Mathematical models; Mechanical and acoustical properties of condensed matter; Mechanical properties of solids; Physics; Pinning; Strain; Stress concentration; Translations; Elastic fields; Edge dislocations; Solid solutions; Strain energy; Strain distribution; Stress effects; Dislocation pinning; Partial dislocation; Elastic deformation; Burgers vector
• ISSN: 1478-6435; 1478-6443
• DOI: 10.1080/14786435.2014.951711

A correct solution for a dislocation atmosphere is provided using Hirth's Standard Model, confirming the errors in Hirth and Lothe. Contrary to what is given there, concentration changes in Cottrell atmospheres reduce an edge dislocation's stress and its elastic energy, thereby reducing the magnitude of the concentration changes. The chemical and elastic strain fields from Cottrell atmospheres are again shown to behave as partial dislocations with variable Burgers vectors that are not crystal translation vectors. The reality of partial dislocations provides a simpler explanation for pinning of dislocations by atmospheres. Much of the literature on dislocation properties in solid solutions should be re-examined.