Growth of α-Fe-Co particles on [001] symmetric tilt boundaries in Cu bicrystals

The kinetics of the coarsening of alpha -Fe-Co precipitate particles on different [001] symmetric tilt boundaries has been investigated using Cu-Fe-Co alloy bicrystals (composition Cu-1.4Fe-0.6Co in mass %) aged at 673, 698 and 723K. The conclusions of this study are summarized as follows. The aging time t dependence of the mean particle radius r can be represented by r exp n =Kt, where K is a constant. The power n is 4 irrespective of misorientation angle and aging temperature. This value is in agreement with the growth theories of boundary particles. The measured activation energy Q and calculated pre-exponential factor D sub 0 of grain-boundary diffusivity against misorientation angle curves display several cusps, and these curves are analogous to the boundary energy against misorientation angle curve. A higher-energy boundary has a higher diffusivity with a smaller value of Q and a smaller value of D sub 0 .