Their research was published in the journal Materialia.
As explained by the BelSU scientists involved in the project, high-entropy alloys (HEAs) are alloys that consist of several metals in approximately equal quantities. Refractory high-entropy alloys (RHEAs) based on refractory metals demonstrate unique mechanical properties at high temperatures due to a combination of characteristics of atoms in different elements.
Therefore RHEAs can be used to manufacture components (discs, blades, and rings) for the hot portion of gas turbine engines for aviation and power engineering.
Researcher at the Laboratory of Volumetric Nanostructural Materials, NRU BelSU, Candidate of Technical Sciences Yurchenko Nikita Yuryevich. Investigation of the microstructure of the developed refractory high-entropy alloy using the FEI Nova NanoSEM 450 scanning electron microscope
© Photo : The National Research University "Belgorod State University" (BelSU)
RHEAs, however, have not yet been used for this purpose because their simple structure makes it impossible to control their properties.
The scientists from BelSU's Nanostructured Materials and Nanotechnologies Science Laboratory came up with a method to manufacture RHEAs. According to them, they have found a microstructural design that makes it possible to obtain more balanced mechanical properties of such alloys, bringing them closer to practical application.
"Examining the effect of phase composition on the mechanical properties of the alloy, which consists of niobium, molybdenum, hafnium, and cobalt, we found that the soft B2 matrix (the fragile component in conventional alloys) inhibits the spread of cracks and contributes to high ductility at room temperature. In turn, BCC lattice solid particles (a soft phase in conventional alloys) strengthen the alloy at high temperatures", Nikita Yurchenko, a scientist from BelSU's Nanostructured Materials and Nanotechnologies Science Laboratory and Candidate of Technical Sciences said.
As the university experts explained, the "inverted" microstructural design allows mechanical properties unique to refractory RHEAs to be obtained. The scientists believe that their method can be implemented for other alloys as well.
The study was supported by the Russian Scientific Foundation under project No. 19-79-30066. The researchers created their new RHEAs and improved their properties in accordance with BelSU's developmental strategy under the Russian government's "Priority-2030" programme.