Simultaneously Enhanced Damping and Stiffness of Amorphous Diaphite.

High-performance damping materials are crucial for numerous applications, yet traditional materials often face a fundamental trade-off between the damping properties and stiffness/strength. Since damping properties of material rely on its inner viscoelastic energy dissipation, it is antagonistic for damping material sustaining high mechanical loads. Recently, an amorphous carbon known as amorphous diaphite (a-DG) was reported, featuring a heterogeneous two-phase composition of nanodiamonds and disordered multilayer graphene (ND/DMG). The a-DG demonstrated diverse microstructure topologies and integrated characteristics, making it a promising candidate for achieving efficient energy dissipation in high-stiffness/strength materials. Herein, we conducted atomistic-based simulations to elucidate the mechanical and damping properties in a-DGs with tunable two-phase structures. Utilizing cyclic loads and Voigt-Reuss-Hill theory, we found that a-DGs exhibit surpassing stiffness and damping capabilities simultaneously, with excellent specific elastic modulus due to lightweight (2.39-3.25 g/cm). The distinguishing performance is attributed to a balanced combination of flexible DMG and stiff ND grains, which can be tuned through manifesting the hybridization. Specifically, the concentrated shear strains, phase transformation and interfacial hybrid bond conversion significantly enhance internal friction through various relaxation mechanisms, while ND grains ensure high stiffness through blocking the propagation of shear bands. The insights obtained here should provide theoretical support for the design and application of high-performance damping materials, opening up an enticing perspective for investigating other amorphous carbons.