Ryoichi Monzen1, Kazuo Kitagawa1, Masaharu Kato2 and Tsutomu Mori2
1Department of Mechanical Systems Engineering, Kanazawa University, Kanazawa
The boundary precipitation of BCC Fe-Co precipitates in a Cu-1.4Fe-0.6Co alloy has been studied, using  symmetric tilt and  twist boundaries. The misorientation angle dependence of the density of the precipitates is similar to that of the boundary energy in Cu for the two types of boundaries. In general, the lower the boundary energy, the lower the density of the precipitates. The minima of the density exist where the cusps of the boundary energy exist; θ=70.5°(Σ 3) and 130°(Σ 11) for  tilt and θ=13°(Σ 41), 23°(Σ 13), 28°(Σ 17), 37°(Σ 5) and 44°(Σ 29) for  twist boundaries. The boundary energy plays a predominant role in governing the boundary precipitation, except for the 130.5° tilt boundary. In the latter case the density of the precipitates is high, because the precipitates can have the K-S orientation relationships to both abutting grains. Accordingly, the precipitates have two flat habit planes with a low interfacial energy. The general shapes of the precipitate density, volume and the PFZ width vs the misorientation angle curves are similar in the two types of boundaries.
grain boundary precipitation, boundary energy, habit plane, copper-iron-cobalt alloy, bicrystals, symmetric tilt boundaries, twist boundaries
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