Citation: Agureev, L.; Kostikov, V.; Savushkina, S.; Eremeeva, Z.; Lyakhovetsky, M. Preparation and Study of Composite Materials of the NiAl-Cr-Mo-Nanoparticles (ZrO 2 , MgAl 2 O 4 ) System. Materials 2022, 15, 5822. https://doi.org/10.3390/ ma15175822 Academic Editors: Dina Dudina and Arina V. Ukhina Received: 5 July 2022 Accepted: 20 August 2022 Published: 24 August 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). materials Article Preparation and Study of Composite Materials of the NiAl-Cr-Mo-Nanoparticles (ZrO 2 , MgAl 2 O 4 ) System Leonid Agureev 1, * , Valeriy Kostikov 2 , Svetlana Savushkina 3 , Zhanna Eremeeva 2 and Maxim Lyakhovetsky 3 1 Department of Nanotechnology, Keldysh Research Center, Moscow 125438, Russia 2 National University of Science and Technology MISIS, Moscow 119049, Russia 3 Moscow Aviation Institute, National Research University, Moscow 125993, Russia * Correspondence: trynano@gmail.com Abstract: Materials based on the NiAl-Cr-Mo system with zirconium oxide or aluminum-magnesium spinel nanoparticle small additions were obtained by spark plasma sintering. Thermodynamic modeling was carried out to predict the phase formation in the NiAl-Cr-Mo system and its change depending on temperature, considering the presence of a small amount of carbon in the system. The phase composition and microstructure of materials were studied. NiAl (B2) and CrMo phases were found in the sintered samples. Bending strength measurements at different temperatures shows that nanoparticles of insoluble additives lead to an increase in bending strength, especially at high temperatures. A fractographic analysis of the sample’s fractures shows their hybrid nature and intercrystalline fracture, which is confirmed by the clearly visible matrix grains similar to cleavage. The maximum strength at 700 ◦ C (475 MPa) was found for material with the addition of 0.1 wt.% zirconium oxide nanoparticles. In the study of internal friction, typical peaks of a nickel-aluminum alloy were found in the temperature ranges of 150–200 ◦ C and 350–400 ◦ C. Keywords: composite material; intermetallic compound; spark plasma sintering; nanoparticles; Young’s module; bending strength 1. Introduction Nickel-aluminum materials are promising for different parts of the manufacture of power plants and engines operating at high temperatures and in aggressive media. Com- pared to nickel alloys, the NiAl intermetallic compound has a high melting point (1911 K) and low density, a high heat resistance up to 1273 K, and good thermal conductivity (70–80 W/(m·K) at temperature range 25–1127 K) [1–4]. The NiAl compound has a density of 5.7–6.3 g/cm 3 and its operating temperature can reach 1000–1100 ◦ C. In addition, the ma- terial has good high-temperature strength, corrosion resistance, and creep resistance [5–9]. However, nickel-aluminum is non-plastic and brittle at room temperature, which reduces the possibility of its application [10–13]. There are several ways to improve the character- istics of this material using additives of transition, rare-earth, and noble metals [14–20]. The development of so-called eutectic alloys based on NiAl containing Cr, Mo and other elements improves its functional properties [12]. Eutectic materials in the NiAl-Cr-Mo system have high thermodynamic stability [14–17,21]. Intermetallic compounds have a high potential for use in composites with high heat re- sistance and high-temperature strength for rocket and space technology, power engineering and the aircraft industry [22,23]. In addition to its attractiveness as an engineering mate- rial, NiAl has such important properties as a simple crystalline structure, a high-ordered crystalline lattice, stability over a wide range of concentrations, a reversible shape memory effect, and anisotropic elastic and plastic behavior. Casting, rapid crystallization, powder metallurgy and mechanical synthesis are used to obtain materials based on NiAl. Limited plasticity and impact strength at room temperature make them difficult to manufacture Materials 2022, 15, 5822. https://doi.org/10.3390/ma15175822 https://www.mdpi.com/journal/materials