Effect of Al Content on Phase Compositions of FeNiCoCrMo<sub>0.5</sub>Al<i><sub>x</sub></i> High Entropy Alloy
Anton Semikolenov,
Svetlana Shalnova,
Victor Klinkov,
Valentina Andreeva,
Maria Salynova,
Tatiana Larionova,
Oleg Tolochko
Affiliations
Anton Semikolenov
Institute of Mechanical Engineering, Materials and Transport, Peter the Great St. Petersburg Polytechnic University (SPbPU), Polytechnicheskaya 29, 195251 St. Petersburg, Russia
Svetlana Shalnova
Institute of Laser and Welding Technologies, State Marine Technical University, Lotsmanskaya Ulitsa, 10, 190121 St. Petersburg, Russia
Victor Klinkov
Institute of Mechanical Engineering, Materials and Transport, Peter the Great St. Petersburg Polytechnic University (SPbPU), Polytechnicheskaya 29, 195251 St. Petersburg, Russia
Valentina Andreeva
Institute of Mechanical Engineering, Materials and Transport, Peter the Great St. Petersburg Polytechnic University (SPbPU), Polytechnicheskaya 29, 195251 St. Petersburg, Russia
Maria Salynova
Institute of Mechanical Engineering, Materials and Transport, Peter the Great St. Petersburg Polytechnic University (SPbPU), Polytechnicheskaya 29, 195251 St. Petersburg, Russia
Tatiana Larionova
Institute of Mechanical Engineering, Materials and Transport, Peter the Great St. Petersburg Polytechnic University (SPbPU), Polytechnicheskaya 29, 195251 St. Petersburg, Russia
Oleg Tolochko
Institute of Mechanical Engineering, Materials and Transport, Peter the Great St. Petersburg Polytechnic University (SPbPU), Polytechnicheskaya 29, 195251 St. Petersburg, Russia
The FeCoNiCrMo0.5Alx system with x up to 2.13 was analyzed from the point of view of evolution of the phase composition and microstructure. Cast samples were synthesized by induction melting and analyzed by X-ray diffraction, energy dispersive spectroscopy, scanning electron microscopy, and Vickers microhardness test methods. Phase compositions of these alloys in dependance on Al concentration consist of FCC solid solution, σ-phase, NiAl-based B2 phase, and BCC solid solution enriched with Mo and Cr. Phase formation principles were studied. Al dissolves in a FeCoNiCrMo0.5 FCC solid solution up to 8 at.%.; at higher concentrations, Al attracts Ni, removing it from FCC solid solution and forming the B2 phase. Despite Al not participating in σ-phase formation, an increase in Al concentration to about 20 at.% leads to a growth in the σ-phase fraction. The increase in the σ-phase was caused by an increase in the amount of B2 because the solubility of σ-forming Mo and Cr in B2 was less than that in the FCC solution. A further increase in Al concentration led to an excess of Mo and Cr in the solution, which formed a disordered BCC solid solution. The hardness of the alloys attained the maximum of 630 HV at 22 and 32 at.% Al.
