OBRABOTKA METALLOV

The peculiarities of the behavior of the powder mixtures of metals and metal matrix composites during Spark Plasma Sintering (SPS) using Ti₃SiC₂-Cu, Fe-Ag, NiO-Ni, Cu₂O-Cu, and Fe-Al systems as examples are analyzed in the work. The physical and chemical aspects of the formation of contacts between composite agglomerates obtained by mechanical treatment of the powder mixtures in a high-energy ball mill and the possibilities of the SPS method for the production of metal matrix composites combining different strengthening mechanisms are discussed. In the Ti₃SiC₂-Cu composites obtained by mechanical milling and SPS, the copper matrix remains in the nanocrystalline state, and the total contribution of dislocation and grain boundary strengthening is greater than the contribution of dispersion strengthening. Microstructural studies of the sintered Ti₃SiC₂-Cu and Fe-Ag compacts show that during SPS of mechanically milled powders, areas of inter-agglomerate contacts can experience melting. In the systems capable of interfacial interactions, the latter preferentially occur at the inter-agglomerate contacts. The conditions for the efficient reduction of oxide films present on the surface of metallic particles during the SPS using a partially oxidized copper powder containing Cu₂O and a partially oxidized nickel powder containing NiO are examined. It is found that under the SPS conditions commonly used in the consolidation practice of metallic powders, elimination of oxide films present on the surface of metallic powders is due to chemical reduction of the oxides by carbon. It is experimentally shown, that reactive pressureless SPS can produce porous materials of high open porosity.

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