Analysis of the Formation of Shape and Structure Defects in Spherical Nickel Monoaluminide NiAl Powders during Their Production

The appearance of defects in nickel monoaluminide NiAl granules during various processes of production of spherical granules is analyzed. The technological processes of producing granules are considered from the point of view of manufacturing high-quality raw materials. Quality criteria for producing nickel monoaluminide NiAl granules are determined. They include the minimum number of granules with internal porosity and other shape defects, high sphericity of particles, high stability of the particle sizes, the absence of satellites on the granules surface, the presence of a fine dendritic structure of the granule material, and so on. Several methods for producing nickel monoaluminide NiAl granules were investigated from the point of view of producing high-quality raw materials. The influence of cooling intensity and granule solidification rates on the dispersion of the material structure and the optimum parameters of centrifugal spraying of a rotating electrode, which ensure the production of high-quality granules, are determined. A developed and tested technology for producing a high-quality spherical NiAl material powder is proposed.