The influence of Cr2AlC max phase additives on the mechanical properties and oxidation capacity of the medium-entropy VNiCo alloy.

DOI: 10.62564/M4-MS1348

Maria Saviak^1,2, Angel Vicente Escuder², Vicente Amigó Borrás<sup>2

1</sup>Frantsevich Institute for Problems of Materials Science National Academy of Science of Ukraine
²Instituto de Tecnología de Materiales, Universidad Politécnica de Valencia, Spain


FCC high-entropy alloys (HEA) have significant plasticity, deformation, but their yield strength should be higher. The strength of high-entropy alloys is due to lattice distortion due to the different sizes of the atoms. The dimensions of the vanadium atom are significantly different from the dimensions of nickel and cobalt, and if vanadium is introduced into their composition, a significant distortion of the lattice while preserving the fcc structure [1]. Equiatomic alloy VNiCo, showed a yield strength of 1GPa [1]. This yield point is reached in alloys with a grain size of 2 μm. The powder metallurgy method makes it possible to obtain HEA with fine grains. Medium-entropy equiatomic alloy VNiCo was obtained by pressing the initial powders under a pressure of 1000 MPa, followed by sintering at a temperature of 1300º C in a vacuum. Cr 2 AlC MAX- phase powder was added to the mixture of initial powders in the amount of 1, 4 mol.%. Cr 2 AlC was obtained in a single-phase state using mechanical activation in a planetary mill followed by heat treatment of the mechanically activated mixture. Oxidation of samples VNiCo, VNiCo with 1, 4% Cr2AlC was carried out in air at temperature of 900ºC for 1, 4, 8, 24, 48, 96 hours. The results. XRD analysis showed after sintering, fcc structure and an average grain size of 50 μm. Porosity after sintering was 15%. The VNiCo alloy showed a yield strength of 800 MPa, a Young's modulus of 108GPa, and a plasticity of 3%. In the presence of 4 mol. % Cr 2 AlC additives, the yield strength decreased to 620 MPa. The oxidation of the VNiCo alloy corresponds to the power function of film growth. The presence Cr 2 AlC in the alloy slows down the rate of oxidation. The oxidation with 1,4% Cr 2 AlC corresponds to the logarithmic law of oxide film growth. The oxides Ni 3 O 8 V 2 , Ni 0.66 O 3 V 1.34 and Co 0.885 O 2 are formed on the surface of the oxidized VNiCo within 96 hours. On the surface of the alloys containing Cr 2 AlC oxide enriched with Cr is formed

Keywords
Medium-entropy alloy, VNiCo, Cr2AlC

Acknowledgments
Not provided

References
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