DOI: 10.18503/1995-2732-2026-24-2-138-145
Abstract
Problem Statement (Relevance). The development of new structural materials with an optimal balance of strength and ductility is one of the key challenges of modern materials science. Medium-entropy alloys of the Co-Cr-Ni system are of considerable interest; however, their properties can be further enhanced through microalloying with elements causing significant atomic lattice distortions, such as niobium and manganese. Understanding the influence of such additives on the structure and mechanical behavior is an important scientific task. Objectives. The research is aimed at investigating the possibility of controlling the mechanical properties of medium-entropy alloys of the Co-Cr-Ni system through controlled alloying with small additions of niobium and manganese (2–6 at.%). Methods Applied. Four alloys of the Nb-Mn-Ni-Co-Cr system have been obtained by vacuum casting followed by remelting for homogenization. Mechanical properties have been studied using uniaxial tensile testing at room temperature, as well as micro- and nanoindentation techniques (according to ISO 14577) to determine hardness and elastic modulus. Fractographic analysis of fracture surfaces has been carried out using scanning electron microscopy. Originality. For the first time, the effect of combined alloying with niobium and manganese on the complex mechanical properties of Co-Cr-Ni-based medium-entropy alloys has been systematically studied. Correlations between elemental composition, hardness, tensile strength, and fracture behavior have been established. Result. It has been found that the addition of niobium leads to solid-solution strengthening due to atomic lattice distortions. The highest values of microhardness (140.7 HV), nanohardness (2.29 GPa), and Young’s modulus (156 GPa) have been obtained for the Nb₂Mn₂Ni₃₆Co₄₀Cr₂₀ composition. The maximum ultimate tensile strength (641 MPa) at relatively low hardness has been demonstrated by the Nb₂Mn₂Ni₃₀Co₄₀Cr₂₆ alloy, indicating a favorable combination of strength and ductility. Fractographic analysis has confirmed a predominantly ductile fracture mechanism. Practical Relevance. The obtained results demonstrate that controlled alloying with niobium and manganese is an effective approach for tailoring the strength-ductility balance in medium-entropy alloys, opening prospects for the development of new structural materials with targeted performance characteristics.
Keywords
Medium-entropy alloy of the Co-Cr-Ni-Mn-Nb system, microstructure, nanohardness, uniaxial tension.
For citation
Konovalov S.V., Drobyshev V.K., Panchenko I.A., Vorobyov S.V., Yu J. Evolution of Mechanical Properties of Medium-Entropy Alloys of the CoCrNbMnNi System. Vestnik Magnitogorskogo Gosudarstvennogo Tekhnicheskogo Universiteta im. G.I. Nosova [Vestnik of Nosov Magnitogorsk State Technical University]. 2026, vol. 24, no. 2, pp. 138-145. https://doi.org/10.18503/1995-2732-2026-24-2-138-145
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