Peculiar microstructure with high damping capacity for Al0.5CrFe2Ni medium-entropy alloy

In this paper, the effect of Al mole ratio on phase evolution, damping capacity and mechanical properties of the AlxCrFe2Ni (indicated by Alx, x = 0.3, 0.4, 0.5 and 0.7) medium-entropy alloys (MEAs) was investigated. The results show that the structure of the Alx MEAs changes from the face-centered cubic (FCC) phase dominated by the Al0.3 alloy to the body-centered cubic (BCC) phase dominated by the Al0.7 alloy. As the volume fraction of the BCC phase increases the corresponding grain size of the alloys decreases and then increases, which increases the ferromagnetic properties and decreases interfacial area in the Alx alloys. The high damping capacity of Al0.5 and Al0.7 alloys is corresponding to 0.05545, and 0.05044, respectively, under the synergistic effects of ferromagnetic damping and interfacial damping. The special honeycomb-like morphology of FCC phase distributed in the BCC matrix gives the Al0.5 alloy the highest damping capacity and yield strength.