AlxCrFeNi medium entropy alloys with high damping capacity

In this paper, the phase constituent, damping and compressive properties of as-cast AlxCrFeNi (x = 0.3, 0.35, 0.37, 0.4, 0.5) medium entropy alloys (MEAs) were studied. The results show that the phase constituent changes gradually from a face-centered cubic (FCC) dominated structure to a single body-centered cubic (BCC) structure when x increases from 0.3 to 0.5. A novel mesh microstructure consisted of 88.3 vol% BCC phase as the hard matrix and 11.7 vol% FCC structure as the secondary soft phase was screened out by pinpointing x of 0.37. The combination of hard matrix and soft secondary phase results in a very high damping capacity up to 0.07093 for such Al0.37CrFeNi MEA at the corresponding strain amplitude of 1.5 x 10(-4). Both the grain size of the BCC phase and the grain boundaries where the FCC phase is distributed are important to increase the damping capacity of the MEA. The excellent damping performance and comprehensive mechanical properties indicate that the Al0.37CrFeNi MEA has potential application as a damping material. (C) 2021 Elsevier B.V. All rights reserved.