Microstructures and morphologies of B2-Ordered NiAl(Co) and FeAl(Co)

(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image) Fine dispersion of disordered phases is obtained in a Ni-Al-Co and Fe-Al-Co ternary system. A transmission electron microscopy investigation has been performed in the present work on the precipitation of supersaturated B2-or...

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Published in:Metals and materials international 2013, 19(2), , pp.189-195
Main Authors: Oh, Chang-sup, Han, Chang-suk
Format: Article
Language:English
Subjects:
Dislocation loops
Dispersions
Hardness
Nickel
Phases
Precipitates
Precipitation
Softening
재료공학
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Summary:(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image) Fine dispersion of disordered phases is obtained in a Ni-Al-Co and Fe-Al-Co ternary system. A transmission electron microscopy investigation has been performed in the present work on the precipitation of supersaturated B2-ordered (Ni,Co)Al and [alpha]-Fe in B2-ordered FeAl(Co) with different stoichiometries. Precipitation behavior and hardening were investigated by measuring the hardness variation. The hardness of (Ni,Co)Al and B2-FeAl(Co) increased appreciably by the fine precipitation of (Ni,Co)^sub 2^Al, [alpha]-Fe, and overage softening occurred after prolonged aging. In case of B2-ordered (Ni,Co)Al, the (Ni,Co)^sub 2^Al phase had a hexagonal structure and took a rod-like shape with the long axis of the rod parallel to the 111 directions of the B2 matrix. By aging at temperatures below 873 K, a long period superlattice structure appeared in the hexagonal (Ni,Co)^sub 2^Al phase. The orientation relationship between the (Ni,Co)^sub 2^Al precipitates and the B2-(Ni,Co)Al matrix was (0001)^sub p^//(111)^sub B2^ and ..., where the suffix p and B2 denote the (Ni,Co)^sub 2^Al precipitate and the B2-(Ni,Co)Al matrix, respectively. (Ni,Co)Al hardened appreciably by the fine precipitation of the (Ni,Co)^sub 2^Al phase. On the other hand, in case of B2-FeAl(Co), the disordered [alpha]-Fe phase was present as a precipitate in a B2-FeAl(Co) matrix and had a cubic-cubic orientation with the matrix. At the early aging periods, prismatic dislocation loops formed in the B2-FeAl(Co) matrix. B2-FeAl(Co) matrix was typically hardened by the precipitation of [alpha]-Fe.[PUBLICATION ABSTRACT]
ISSN:1598-9623
2005-4149
DOI:10.1007/s12540-013-2008-z