The present work reports the direct production of a high-entropy (HE) intermetallic CoNi_0.3Fe_0.3Cr_0.15Al material with a B2 structure from mechanically activated elemental powder mixtures. Fast and efficient combustion synthesis (CS), spark plasma sintering (SPS), and reactive SPS (RSPS) methods were used to synthesize the HE powders and bulks. The formation of the main B2 phase along with some amounts of secondary BCC and FCC phases are reported, and L12 intermetallic (CS scheme) and BCC based on Cr (CS + SPS and RSPS schemes at 1000 °C) were observed in all samples. The interaction between the components during heating to 1600 °C of the mechanically activated mixtures and CS powders has been studied. It has been shown that the formation of the CoNi_0.3Fe_0.3Cr_0.15Al phase occurs at 1370 °C through the formation of intermediate intermetallic phases (Al₉Me₂, AlCo, AlNi₃) and their solid solutions, which coincidences well with thermodynamic calculations and solubility diagrams. Compression tests at room and elevated temperatures showed that the alloy obtained by the RSPS method has enhanced mechanical properties (σ_p = 2.79 GPa, σ_0.2 = 1.82 GPa, ε = 11.5% at 400 °C) that surpass many known alloys in this system. High mechanical properties at elevated temperatures are provided by the B2 ordered phase due to the presence of impurity atoms and defects in the lattice.

Comparative investigations of the structural characteristics and functional properties of Ti–Al–Mo–N and Ti–Al–Mo–Ni

Zr–B–Si–C–Ti and Zr–B–Si–C–Ti–N coatings have been produced for the first time by an arc physical vapor deposition process in a residual argon + nitrogen atmosphere. The Zr–B–Si–C–Ti coating had an amorphous–nanocrystalline structure. Nanocrystallites were formed in the Ti–B–C system, and the amorphous component of the material was formed by Zr–B–C and Si–C phases. The coating of the latter system had a predominantly amorphous structure (amorphous content of ~85–93%) based on titanium nitride with Ti–B and Ti–C bonds, zirconium carboboronitride (Zr_x(C,N,B)_y), zirconium boride, and silicon carbonitride.

The influence of nickel on the structure and properties of Ti-Cr-N ion-plasma coatings obtained by arc-PVD method has been studied. With a nickel content of up to 11.9 at. %, the coating consists of Cr₂N, _{Ti1 – x}Cr_xN, and metallic Ni. Upon further increase in Ni concentration in the coating, intermetallic compound Ni3Ti is formed. The structure of the coatings was studied using the transmission electron microscopy. The coatings of Ti-Cr-N system are characterized by a columnar structure, in the columns of which _{Ti1 - x}Cr_xN and Ti_{1 - y}Cr_yN (x > y) sublayers, being several nanometers thick and containing variable concentration of titanium and chromium, as well as Cr₂N sublayers of about 25 nm are formed due to the complete solubility of TiN and Cr₂N and the planetary rotation of the substrates, resulting in layer-by-layer stacking of the components of the evaporated cathodes. This structure remains intact in coatings of Ti-Cr-N-Ni system with a low nickel concentration (on the order of tenths of at. %). However, upon that, the column size refinement and an increase in biaxial compressive stresses from 6.7 to 9.7 GPa are observed, which results in an increase in hardness from 30 to 42 GPa. The coatings with a high nickel content are characterized by a multilayer architecture with an equiaxed polycrystalline structure of nanograins in layers. As Ni concentration increases, the hardness of the coating decreases to 16.7 GPa, which is associated with an increase in the fraction of relatively soft nickel in the coating and a decrease in macrostresses to -0.6 GPa. Upon that, the wear intensity increases from 3·10^-15 to 5·10^-15 m³/(N·m). The studied coatings of Ti–Cr–N and Ti–Cr–N–Ni systems are resistant to adhesive and cohesive destruction. With an increase in the nickel content upon measuring scratching, the destruction of the coatings occurs exclusively due to the plastic deformation.