In recent years, significant progress has been achieved in the study of the anisotropy of elastic properties of nonstoichiometric cubic carbides MC_y (M = Ti, Zr, Hf, Nb, Ta) and monoxides MO_y (M = Ti, Nb). The composition of nonstoichiometric cubic compounds MX_y (X = C, O) determines their electronic structure, mechanical (elastic) properties and possible fields of application in modern engineering. This critical review summarizes recent achievements in the semi-empirical evaluation of elastic characteristics of nonstoichiometric cubic compounds. The main results on the dependences of elastic constants c_i,j on the composition of disordered nonstoichiometric cubic carbides MC_y (M = Ti, Zr, Hf, Nb, Ta) and monoxides MO_y (M = Ti, Nb) are systematized for the first time. The effect of nonstoichiometry on the elastic anisotropy of carbides and monoxides is considered. It is shown that the maxima and minima of the spatial three-dimensional distributions of elastic moduli of the discussed nonstoichiometric cubic compounds are observed in the equivalent directions [±100], [0±10], [00±1] or directions [±1 ±1 ±1], respectively. It is shown that among the considered nonstoichiometric compounds, cubic titanium monoxide TiO_y has the largest anisotropy of elastic properties, which is a plastic material in terms of the ratio of shear and bulk moduli. An empirical relationship between the elastic stiffness constants c_ij of nonstoichiometric cubic carbides MC_y and their melting temperature is proposed.

Typically, an English full text is available in about 1 month from the date of publication of the original article.

Keywords: nonstoichiometry, nonmetal sublattice defectivity, elastic properties anisotropy, melting temperature PACS: 46.25.−y, 46.35.+z, 62.20.D−, 62.20.de (all) DOI: 10.3367/UFNe.2025.08.039994 URL: https://ufn.ru/en/articles/2026/2/c/ Citation: Sadovnikov S I, Gusev A I "Anisotropy of elasticity of strongly nonstoichiometric disordered cubic carbides MCy (M = Ti, Zr, Hf, Nb, Ta) and monoxides MOy (M = Ti, V, Nb)" Phys. Usp. 69 (2) (2026) Received: 23rd, May 2025, revised: 9th, July 2025, accepted: 5th, August 2025 Оригинал: Садовников С И, Гусев А И «Анизотропия упругих свойств сильно нестехиометрических неупорядоченных кубических карбидов MCy (M = Ti, Zr, Hf, Nb, Ta) и монооксидов MOy (M = Ti, V, Nb)» УФН 196 149–172 (2026); DOI: 10.3367/UFNr.2025.08.039994