Abstract: Mechanical vibrations and noise pose critical challenges to device reliability and human health, necessitating high-performance materials that dampen vibrations while supporting structural loads. Conventional alloys struggle to achieve high damping (tanδ > 0.02), high strength (> 1 GPa), and good ductility (> 15 %) simultaneously, due to the intrinsic trade-off governed by defect motion. Here, we introduce a multi-scale chemical engineering strategy for Ti-36Nb-0.9O alloys that exhibits an exceptional combination of ultra-high damping peak (tanδ = 0.104, at ∼500 K) and remarkable room-temperature mechanical properties, including a yield strength of 1090 MPa and tensile elongation of 23 %. This breakthrough stems from a dual-domain hierarchical structure, comprising alternating strip-like (α+β) regions and single β regions. The strategically distributed α phase facilitates Nb and O redistribution, while thermal-kinetic modulation in the oxygen-enriched β region induces spinodal decomposition, resulting in nanoscale chemical fluctuations that amplify conventional Snoek relaxation. The combination of strength and damping capacity in this work is highly competitive among existing structural materials. Additionally, localized α precipitation leads to compositional heterogeneity, enhancing oxygen solubility, which synergistically strengthens the alloy through interstitial solid solution strengthening and hetero-deformation-induced strengthening. Most importantly, the engineered β phase stability gradient enables the sequential activation of multiple deformation mechanisms, including phase transformation, twinning, and dislocation slip, leading to an optimal balance of mechanical properties. This innovative strategy opens new avenues for developing advanced multifunctional structural metals with tailored vibration-damping and load-bearing capabilities.

Key words: Titanium alloys, Ultra-high damping, Oxygen doping, Spinodal decomposition, Chemical heterogeneity