O.B.Perevalova
,
M.B.Fedorischeva
,
V.E.Ovcharenko
,
Huihe SU
材料科学技术（英文）
By X-ray analysis, TEM and SEM methods the phase composition, microstructure, and deviation from stoichiometric composition were investigated for the Ni3Al intermetallic compound obtained by cast and self-propagation high-temperature synthesis under compression with followed homogenization anneal, with the Al concentration being 24.0 and 25.0 at. pct with and without B (0.5 at. pct). It was discovered that in SHS intermetallic alloys an average local deviation from stoichiometric composition is significantly more than in the cast alloy. Dependence of the local deviation from the stoichiometric composition on the distance has a zig zag nature at the level of the grain groups. Deviation from the stoichiometric composition at the boundaries of the general type is less than at the boundaries of the special type. When the intensity of boundary migrations of the general type decreases, the degree of deviation from the stoichiometric composition increases. There is correlation between the solubility of B in the crystalline lattice of the Ni3Al phase and the value of the deviation from the stoichiometric composition in the grains. When the B concentration in a solid solution increases, the deviation from stoichiometric composition decreases.
关键词:
Ni3Al
,
null
,
null
,
null
M. V.Fedorischeva
,
V.E.Ovcharenko
,
O.B.Perevalova
,
E.V.Kozlov
材料科学技术（英文）
The Ni3B phase was formed when boron (0.5 at. pet B) was added to the intermetallic of stoichiometric and off-stoichiometric (Ni-24 at. pct Al) compounds. In the alloy of stoichiometric composition the particles of Ni3B phase has the size around 0.1 mu m and is located on the grain boundary of the main phase. The decreasing of concentrations of Al in the off-stoichiometric alloy leads to increase in the degree of the long-range order parameter, increasing the concentrations of boron in the solid solution and decreasing its localization on the grain boundary. Microalloying of boron leads to increasing in the fraction of grain monodomains with dislocations up to 0.7 in the alloy of the off-stoichiometric composition and up to 1 in the alloy of the stoichiometric composition. It was established the correlation between the degree of the concentration inhomogeneity, average density of the dislocations and the average long range-order parameter.
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