Concentration Heterogeneity in Structure of Intermetallic Synthesized under Compression

摘要

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 synthesisunder compression with followed homogenization anneal, with the Al concentration being 24.0 and 25.0 at. pct with andwithout B (0.5 at. pct). It was discovered that in SHS intermetallic alloys an average local deviation from stoichiometriccomposition is significantly more than in the cast alloy. Dependence of the local deviation from the stoichiometric compositionon the distance has a zig zag nature at the level of the grain groups. Deviation from the stoichiometric composition at theboundaries of the general type is less than at the boundaries of the special type. When the intensity of boundary migrations ofthe general type decreases, the degree of deviation from the stoichiometric composition increases. There is correlation betweenthe solubility of B in the crystalline lattice of the Ni3Al phase and the value of the deviation from the stoichiometric compositionin the grains. When the B concentration in a solid solution increases, the deviation from stoichiometric composition decreases.