Additive manufacturing-induced anisotropy in damping performance of a dual-phase high-entropy alloy

Additive manufacturing (AM) can endow materials with specific microstructures, inducing anisotropy. In this study, we employed the AM technique to fabricate a dual-phase high-entropy alloy (HEA) and evaluated the damping properties of this alloy cut parallel and perpendicular to the building direction (denoted as BD and TD, respectively) while considering strain amplitude and temperature. Results reveal the presence of two distinct damping peaks as temperature increases. At low temperatures, the damping behavior is primarily controlled by dislocation movements. At moderate and high temperatures, damping performance is governed by phase transformation and grain boundary sliding. The maximum difference of damping capacity between BD and TD samples reached 247.8%. This variation can be attributed to the introduction of columnar grain microstructures along the BD by AM, increasing the average distances for dislocation movement. In addition, the intensification of phase transformation and grain boundary sliding results from more vigorous dislocation movement in BD samples, with rising temperatures, contributing to superior damping performance. Moreover, a model was developed to illustrate the temperature-dependent variations in the damping performance of this dual-phase HEA. This model elucidates the damping mechanisms within different temperature ranges and the origin of damping anisotropy. The insights derived from this study bear significance for the design of innovative HEAs, which can broaden their applications.