Constructing dual-scale high-entropy alloy/polymer interpenetrating networks to develop a lightweight composite with high strength and excellent damping capacity

[Display omitted] •The dual-scale CrMnFeCoNi/polymer interpenetrating phase composite (IPC) was developed.•The IPC-2 exhibits a compressive strength of 37.2 MPa and an energy absorption capacity of 22.5 MJ·m−3 (ε = 65 %), with a mere density of 2.528 g·cm−3.•The IPC-2 exhibits a loss factor exceeding 0.132 with a peak value of 0.206 within 20 ∼ 150℃.•The coupling of multi-scale intrinsic damping and interface damping endows the composite with high ground-state damping.•The phase transformation peak of CrMnFeCoNi foam and the glass transition peak of polymer enables a wide damping temperature window. Lightweight materials with high strength and excellent damping capacity are of great significance for reducing weight and vibration and maintaining stability in industrial applications. However, these characteristics are usually difficult to achieve simultaneously in traditional damping materials. Here, we provide a design strategy for dual-scale interpenetrating networks. By infiltrating the viscoelastic polymer containing CrMnFeCoNi nanoalloy/carbon nanotube networks into CrMnFeCoNi high-entropy shape memory alloy foam with a three-dimensional network structure, the dual-scale CrMnFeCoNi/polymer interpenetrating phase composite was developed. When the carbon nanotube loading is 2 wt%, the composite exhibits a compressive strength of 37.2 MPa and an energy absorption capacity of 22.5 MJ·m−3 (ε = 65 %), with a mere density of 2.528 g·cm−3. In the temperature range of 20 ∼ 150℃, its loss factor exceeds 0.132 with a peak value of 0.206. Compared with CrMnFeCoNi foam, its compressive strength, energy absorption capacity and peak internal friction are increased by 85 %, 65 % and 156 %, respectively. The construction of dual-scale interpenetrating networks introduces high-density interfaces, and the coupling of multi-scale intrinsic damping and interface damping endows the composite with high ground-state damping. The superposition of the phase transformation peak of CrMnFeCoNi foam and the glass transition peak of polymer composite matrix enables a wide damping temperature window. This study offers a new perspective for developing high-performance damping materials.