The kinetic theory of isothermal atomic transport via point defects that was presented in two previous papers (Franklin, A. D. & Lidiard, A. B.
Proc. R. Soc. Lond
. A 389, 405–431 (1983) and Franklin, A. D. & Lidiard, A. B.
Proc. R. Soc. Lond
. A 392, 457–473 (1984)) has been expanded into a three-dimensional formulation to analyse transport in an applied non-uniform stress field. The fluxes of the various defect species take the general form familiar from non-equilibrium thermodynamics, while the contribution to the force on defect species Y arising from the stress σ
αβ
is confirmed to be
v
∇(λ
(Y)
αβ
σ
αβ
), where
v
is the molecular volume of the solid and λ
(Y)
αβ
is the elastic-dipole strain tensor of the defect species Y (summation over repeated Cartesian indices
α, β
is here assumed). Full details of these calculations are presented in Lidiard, A. B.
A. E. R. E. Rep
. no R. 11367 (1984).