OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 26 No. 2 2024 TiC. The cubic lattice parameter decreases as the elemental composition of the carbide moves away from the equiatomic one [35, 36]. The lattice parameter of α-iron is close to the reference value, i.e. 0.2866 nm. The microstructure of sintering materials is shown in figure 2. With pressureless sintering, it is not possible to obtain a dense material. In the optical metallography images (fig. 2 a, b), areas ranging in size from several up to tens of microns, separated by epoxy-filled pores, are visible. In the backscattered electron microscopic images in figure 2, c, d, the iron binder and titanium carbide are clearly distinguishable due to the tonal contrast: heavy iron appears lighter than carbide consisting of lighter elements. In Table 1 we marked the Fe2Ti + C composition as composite No. 1 and the FeTi + C composition as composite No. 2. In the structure of composite No. 1, which has a larger volume fraction of the binder, carbide inclusions of micron and submicron size are located predominantly in the volume of the binder (fig. 2, a, c). Due to the small size of carbide inclusions, it is difficult to accurately determine its elemental composition. The dispersed structure of composite No. 2, containing a larger volume fraction of the carbide phase, can be discerned only at high magnification (fig. 2, d). Submicron carbide inclusions in the composite No. 2, as well as in the composite No. 1, are located in the volume of the binder (fig. 2, d), but because of the great volume fraction of the carbide phase in composite No. 2, some of it are located outside of the composite granules. In the volume of the binder in figure 2, d, an unidentified phase is visible in the form of lighter lamellas. It is possible, that is austenite lamellas, weak lines of which are present in the X-ray diffraction pattern (fig. 1, b). The elemental composition of the binder in composite No. 1 was evaluated by EDX point analysis in a few areas free of carbide particles (fig. 3). According to local elemental analysis data given in Table 2, the binder has a significant carbon content. The probable reason for the increased carbon content in α-Fe is the influence of titanium, which, according to the phase diagram of the Fe-Ti system [34], is a strong а b Fig. 1. X-ray patterns of compacts sintered (1.200 °C, 60 min) from mechanically activated Fe2Ti + C (a) and FeTi + C (b) mixtures Ta b l e 1 Phase composition (vol. %) of products of sintered compacts from mechanically activated Fe2Ti + C and FeTi + C mixtures № Mixture composition Volume content of phases, % Lattice parameters, nm TiC α-Fe Others TiC α-Fe 1 Fe2Ti + С 45 54 1.0 (Ti) 0.43173 0.28676 2 FeTi + С 57.3 40.3 0.8 (γ-Fe), 1.6 (FeTi) 0.43204 0.28696
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