Strengthening of AlCoCrFeNi based high entropy alloy with nano- Y2O3 dispersion

In this research, Y2O3-reinforced (0, 1, 2, 3 wt%) AlCoCrFeNi high entropy alloys (HEAs) were synthesized using mechanical alloying (MA) and spark plasma sintering (SPS) technique. After 40 h of milling, the phase aggregate combines a body centred cubic (BCC) solid solution structure and face centred cubic (FCC) for all the four alloys and minor presence of Al4FeO12Y3 garnet phase in the alloys containing Yttria (1–3 wt%). After the consolidation by SPS method at 1000 °C, σ phase was also observed. Meanwhile, the Garnet phase was retained during consolidation. With the help of X-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis, it was observed that the inclusion of Yttria particles has a constricting outcome on the grain growth of alloy during SPS. The average grain size measured varies from 203 nm to 151 nm for 0 and 3 wt% dispersed alloy respectively. The present Yttria dispersed alloys show improved hardness and yield strength of 879 ± 4 HV and 1032 ± 11 MPa respectively for 3 wt% Yttria dispersion. The novelty of Yttria dispersed alloys resides in the microstructure containing the Al4FeO12Y3 particles with uniform distribution.