Diffusion-Drift Effect on Grain Boundary Grooving

Diffusion-drift effect is a fast diffusion penetration along grai n boundaries (GB) due to the concentration gradient and the force causing drift with the rate V = const. Earlier the problem was discussed with the use of two dimensionless parameters δ β / 4Dt = and t D Vt b 4 / = γ where D and Db are the coefficients of bulk and GB diffusion, δ is GB width and t is the time. In this paper a fresh portion of the solution is introduced into the denominat or of β which is now equal to δ s , where s is the segregation coefficient: C C s b / = , where C and Cb are the bulk and GB concentrations of diffusant. The numerical solutions of the problem are obt ained for different and . These solutions are applied to the process of GB grooving. The region is l mited of such , values when the drift flux predominates and the long step exists at GB solute concentration profiles. The main contradictions of the problem are discussed. If the drift ef fect is significant it may probably explain a cracks formation without external stresses.

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