The structure and mechanical properties of as-cast and thermomechanicaly processed (cold rolling followed by annealing at 700 °C and 900 °C) Fe₄₀Mn₄₀Cr₁₀Co₁₀ (at.%) high-entropy alloys doped with different amounts (0, 0.5, and 2.0 at.%) of N were examined. The as-cast Fe₄₀Mn₄₀Cr₁₀Co₁₀ alloy (N0) contained σ-phase particles at the boundaries of the fcc grains. The addition of 0.5 (N0.5) and 2.0 (N2) at.% of nitrogen suppressed the formation of the σ-phase due to which the alloys consisted of only the fcc phase. Annealing after rolling resulted in the development of static recrystallization and precipitation of additional phases: the σ-phase was found in the N0 and N0.5 alloys, and hexagonal M₂N nitrides were found in the N2 alloy. The strength of the as-cast alloys at room temperature increased with increasing nitrogen concentration due to interstitial solid solution strengthening. Cold rolling and subsequent annealing resulted in considerable strengthening of the program alloys. The strength of the alloys increased with the N content and decreased with increasing annealing temperature. The best combination of mechanical properties at room temperature was attained in the N2 alloy after annealing at 700 °C, and at 77 K, was demonstrated by the N0.5 alloy after annealing at 900 °C.

The NiAl–Cr–Co–X alloys were produced by centrifugal self-propagating high-temperature synthesis (SHS) casting. The effects of dopants X = La, Mo, Zr, Ta, and Re on combustion, as well as the phase composition, structure, and properties of the resulting cast alloys, have been studied. The greatest improvement in overall properties was achieved when the alloys were co-doped with 15% Mo and 1.5% Re. By forming a ductile matrix, molybdenum enhanced strength characteristics up to the values σ_ucs = 1604 ± 80 MPa, σ_ys = 1520 ± 80 MPa, and ε_pd = 0.79%, while annealing at T = 1250 ℃ and t = 180 min improved strength characteristics to the following level: σ_ucs = 1800 ± 80 MPa, σ_ys = 1670 ± 80 MPa, and ε_pd = 1.58%. Rhenium modified the structure of the alloy and further improved its properties. The mechanical properties of the NiAl, ZrNi₅, Ni_0.92Ta_0.08, (Al,Ta)Ni₃, and Al(Re,Ni)₃ phases were determined by nanoindentation. The three-level hierarchical structure of the NiAl–Cr–Co+15%Mo alloy was identified. The optimal plasma treatment regime was identified, and narrow-fraction powders (fraction 8–27 µm) characterized by 95% degree of spheroidization and the content of nanosized fraction <5% were obtained.

The influence of different methods of producing alloys of the Fe–Cu system from immiscible components is studied. Alloys with limited solubility (LS)

The influence of the remelting temperature on the structural heredity of the alloy fabricated by centrifugal SHS metallurgy is investigated. It is shown by the example of the highly boron-alloyed...

Fe–Cu alloys can be characterized as a system with immiscible components (IC). This statement is based on a weak mutual solubility in the solid state

We investigate the melting ranges of the base Zr–Si mixture (eutectic composition) depending on the content of the heterophase powder component in the ZrB₂–ZrSi₂–MoSi₂ and the HfB₂–HfSi₂–MoSi₂ systems in the amount of 30–90 wt % obtained by self-propagating high-temperature synthesis (SHS). The range of the melting point of the Zr–Si mixture was 1420–1440°C; addition of the ZrB₂–ZrSi₂–MoSi₂ SHS powders resulted in an increase of the melting onset temperature T_m0 to 1460–1560°C and in the complete melting temperature T_melt to 1480–1670°C. Addition of the HfB₂–HfSi₂–MoSi₂ powders influenced only slightly the T_m0 value (1390–1430°C), but resulted in the increase in T_melt to 1510–1550°C. The X-ray phase analysis shows that the remelted samples contain the following phases: ZrB₂/HfB₂, ZrSi₂/HfSi₂, MoSi₂, and Si; here, the number of phases was directly proportional to the SHS powder content in the Zr–Si mixture. The ingots are characterized by a homogeneous structure consisting of the silicon matrix and ZrSi₂/HfSi₂ and MoSi₂ grains, with inclusions of ZrB₂/HfB₂.