Mechanical Alloying with the Partial Amorphization of the Fe–Cr–Co–Ni–Mn Multicomponent Powder Mixture and Its Spark Plasma Sintering to Produce a Compact High-Entropy Material

Abstract

The results of studying the influence of mechanical alloying (MA) on the surface morphology, microstructure, and atomic–crystalline structure of particles of the Fe–Cr–Co–Ni–Mn multicomponent powder mixture are presented. The initial components are as follows: the R-10 radio-engineering carbonyl iron powder with average particle size d = 3.5 μm, the NPE-1 nickel powder with d = 150 μm, the PK-1u cobalt powder with d < 71 μm, the PKh-1M chromium powder with d < 125 μm, and the MR0 manganese powder with d < 400 μm. The MA of the prepared mixture was performed in an AGO-2 water-cooled mechanical activator using 9-mm steel balls with an acceleration of 90 g in air. The alloying time varies from 5 to 90 min. The ratio of the ball weight to the mixture weight is 20 : 1. X-ray diffraction patterns of the initial and alloyed mixtures, as well as of the sample formed by sintering, are recorded using a DRON 3M diffractometer in FeKα radiation at 2θ = 30–100°. The microstructure of the mixture particles and the compact sample metallographic specimen after sintering are investigated by scanning electron microscopy. It is established that the peaks of initial components are absent in the X-ray diffraction pattern after mechanical activation for 90 min, and peaks corresponding to the phase representing the γ-Fe-based solid solution having a face-centered crystal lattice are presented. Herewith, the fraction of the amorphous phase increases to 20%. A compact single-phase material is formed from the mixture prepared after 90-min alloying by spark plasma sintering at 800°C for 10 min. Its density is 7.49 kg/cm3, resistivity is 0.94–0.96 × 10–6 Ω m, and microhardness is 306–328 kg/mm2. The phase is uniformly distributed over the volume.