The mechanical interaction of a point defect with a surface layer

A relationship is derived which expresses the interaction energy between a source of internal stress and a surface in terms of the elastic field. This is used to consider the mechanical interaction energy between a point defect and a layer of finite thickness on the surface of body. For convenience, the body is taken to be semi‐infinite and isotropic, and the layer is also isotropic but with different elastic constants. The point defect is approximated by a dilatation centre. A transform method is used to obtain the elastic field, and this gives analytic expressions for the interaction energy in the limiting case corresponding to a bicrystal. For situations of finite layer thickness, the energy has been determined numerically for a wide range of values of elastic constants, layer thickness and defect to layer‐matrix interface distance. The conditions which give rise to attraction or repulsion of the defect from the interface have been studied, not only for the case in which the defect is in the matrix but also when it is in the layer.