STUDY OF THE EFFECT OF MOLYBDENUM ON THE PROPERTIES OF THE CO-CR-FE-NI-MN-NB QHEA

*А. R. Abildina1
Abylkas Saginov Karaganda Technical University, Republic of Kazakhstan, Karaganda
ORCID: https://orcid.org/0009-0001-17Q5-1352 *e-mail: aizhan—1984@mail.ru  

This study investigates the effects o f varying molybdenum concentrations (5%, 10 %, and 15 %) on the microstructuralfeatures, hardness, and meltfluidity o fquasi- high-entropy alloys (QHEAs) within the Co-Cr-Fe-Ni-Mn-Nb system. The primary objective is to reduce production costs o f advanced alloys by partially replacingpure elemented constituents with ferroalloys. Experimented ingots were synthesized via induction melting, followed by characterization through scanning electron microscopy (SEM), Brinell hardness testing, and spiralfluidity assessments. Results indicate that increasing Mo content markedly enhances hardness —approaching a threefold increase at 15 % Mo —attributable to solid-solution strengthening and probable intermetallic phase formation. However, elevated molybdenum levels negatively affect melt fluidity, with a reduction o f approximately 12 % observed at Mo contents between 10 % and 15 %, leading to casting defects. These findings emphasize the importance o f optimizing molybdenum concentration to achieve an optimal balance between mechanical performance and castability. For components with complex geometries, maintaining Mo content below- 10 % is advisable. This work contributes to the development ofcost-effective QHEAs suitablefor precision casting using locally sourced materials.