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The CrMnFeCoNi-based composites with different multi-layer graphenes (MLGs) content (0 wt%, 0.2 wt%, 0.4 wt%, 0.6 wt%, 0.8 wt%) were prepared by powder metallurgy. The effects of the MLGs content on the mechanical and damping properties of the composites were studied specifically. The strength and hardness are obviously improved, and the tensile strength can reach 762 MPa. With the addition of MLGs, new damping mechanisms including the intrinsic damping of graphene and the interface damping are introduced, which lead the damping properties of composites to remain at a high level. As the content of MLGs increases, the Maximum internal friction (Q-1max) of the composites increases first and then decreases, and its maximum value is 0.0667.

The Fe65-xMn20Cr15Cox (x = 0, 5, 10, 15) high entropy alloys (HEAs) were prepared by mechanical alloying (MA) and spark plasma sintering (SPS). The effects of the configurational entropy on the microstructure, magnetic properties, and damping behaviors were investigated in this paper. As the Co content increased, the configurational entropy of the HEAs was increased from 0.88R to 1.23R, the magnetology performance was reduced significantly, but the peak of internal friction (IF) Q-1 increased monotonously. The maximum internal friction (IF) Q-1max achieved 0.073 when 15 at% Co element was added. With the configurational entropy increasing, in addition to the ferromagnetic damping mechanism, the dislocation damping mechanism was introduced in the HEAs. The synergistic effect of magneto-mechanical hysteresis and dislocation energy dissipation ensured the FeMnCrCo HEAs maintained high damping performance in a wide strain amplitude. Through the regulation of the microstructure, the possibility of application of the damping alloy under extreme conditions can be expanded.