Influence of the chemical composition of the matrix on the structure and properties of monolithic SHS composites

OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 23 No. 3 2021 Fig. 5. Chemical elements distribution in the composite Fe-Ni-Cr-Ti-C-B: a – image in secondary electrons; b – in the characteristic X-ray radiation Fe; c – Cr; d – Ti; e – C; f – B a b c d e f Conclusions In all the studied composites, the main reinforcing phases are particles of titanium carbide TiC and titanium diboride TiB 2 , formed as a result of the chemical interaction of the initial powders and unevenly distributed in the volume of the composites. The matrix of composites consists of solid solutions based on crystal lattices of Fe, Cr, Ni or Cu. The more metals are included in the matrix, the more heterogeneous the composite is in chemical composition. The Fe-Ni-Cr-Ti-C-B composite system is characterized by the maximum chemical heterogeneity. The introduction of Ni into the iron matrix led to the formation of regions with the eutectic structure of γ-Fe + Fe 2 B and an additional strengthening phase-the intermetallic Ni 3 Ti. The matrix of the Fe-Ni-Cr-Ti-C-B composite system consists of two solid solutions: based on austenite (Fe-Ni) and based on ferrite (Fe-Cr). Chromium carbide Cr 23 C 6 particles formed along the boundaries of austenitic matrix grains were added to the reinforcing particles TiC, TiB 2 and Ni 3 Ti. When forming a composite of the Cu-Ti-C-B system, the synthesis reaction of titanium carbide and diboride was not fully realized. In addition to the TiC and TiB 2 phases, particles of unreacted initial boron carbide B 4 C were recorded in separate volumes of this composite, around which a thin layer of a Cu-based solid solution with boron particles was formed. SHS composites with a matrix consisting of a solid solution with a FCC crystal lattice showed the greatest strength when tested for transverse bending. The abrasive wear resistance of all the studied composites is at the same level. The minimum roughness after testing was recorded for a composite with a copper matrix.