2002 Volume 66 Issue 7 Pages 696-700
The effects of additions of Ag, Cr, Sb and P on the formation and growth of discontinuous precipitation (DP) reaction have been examined for different [001] symmetric tilt boundaries in a temperature range from 623 to 698 K using Cu-0.75 mass%Be alloy bicrystals. As the concentration of each element increases, the incubation period to initiate DP for a boundary increases, the cell growth rate for the boundary decreases, and both reach constant values. A detailed kinetic analysis of DP using the models by Turnbull and Petermann-Hornbogen has enabled to determine the grain-boundary diffusivity. At the stage in which the cell growth rate becomes a constant value, the activation energies Qb for boundary diffusion are in agreement with those Qv for bulk diffusion of the elements in Cu. For boundaries which have values of Qb lager than Qv before adding P, the boundary diffusivity is not affected by the P addition.
