Dynamic origins of anelasticity in LaCeNiAl metallic glass

Elucidating the complex anelastic-to-plastic transition mechanism in metallic glasses (MGs) is crucial for their engineering applications. A core challenge is to establish a unified physical framework that links atomic-scale dynamics to macroscopic mechanical behavior, which requires experimentally and quantitatively decoupling the specific roles and respective contributions of the fast β-relaxation and the slow α-relaxation. This work resolves this challenge by using a LaCeNiAl MG with a prominent β-relaxation. At 340 K, the anelastic recovery shows a distinct two-stage character: a fast, β-relaxation-dominated initial stage followed by slow, α-relaxation-controlled long-time recovery. At higher temperatures, recovery becomes a single-stage process, well described by a power-law distribution of relaxation times, D(τ) ∝ τ^−0.7, originating from the high-frequency wing of the α-relaxation. A unified framework is established by inverting the mechanical spectrum via a generalized Maxwell model, quantitatively predicting the anelastic behavior and clarifying the transition from β- to α-dominated response. This leads to a relaxation time map covering three regimes: β-dominated anelasticity, α-dominated anelasticity and viscoplasticity. The results support a hierarchical picture of atomic motion consistent with the double percolation theory of mobile/immobile regions in glasses, providing a solid experimental and theoretical basis for linking atomic-scale dynamics to macroscopic mechanical behavior.