Spatially Localized Reversible Glass-to-Liquid Transition in Vitreloy 1: A Ginzburg-Landau Study of Acousto-Thermal Coupling

We propose and numerically validate a theoretical framework for a spatially localized, temporally reversible glass-to-supercooled-liquid transition in Vitreloy 1 (Zr₄₁Ti₁₄Cu₁₂Ni₁₀Be₂₃) induced by a focused acousto-thermal external coupling field J(x,t). Using the time-dependent Ginzburg-Landau (TDGL) formalism — specifically the Allen-Cahn relaxation equation — we introduce a scalar order parameter ψ ∈ [0,1] mapping the local icosahedral short-range order (ψ=1, glassy state) to the structurally disordered supercooled liquid (ψ=0). The external field J(x,t), physically implemented as a phased-array focused ultrasound (PAFUS) pulse combined with a localized Joule heating impulse, drives the local temperature above Tg = 623 K, reversing the sign of the Landau coefficient a(T) = a₀(T/Tg − 1) and suppressing the free energy minimum at ψ=1 in spinodal fashion. Key results: — 1D time integration confirms fluidification to ψ_min ≈ 0.90 and subsequent monotonic return toward ψ=1 upon pulse extinction. — 2D finite-difference simulation (100×100 grid) demonstrates spatial confinement of the transition to the focal volume, with a diffuse solid-liquid interface of width ~ξ and no perturbation of the surrounding glassy matrix. — Residual deviation |Δψ| ≈ 0.07 is identified as a kinetic artifact of the finite simulation horizon relative to τ_α(T_amb), not a thermodynamic irreversibility. — Residual free energy |ΔF| < 4% of the inter-phase barrier confirms thermodynamic reversibility. This work provides a quantitative phase-field basis for controlled, non-destructive local processing of bulk metallic glasses and identifies PAFUS-driven spatially selective softening as a promising avenue for precision micro-engineering of amorphous alloys. AI Disclosure: An AI assistant (Anthropic Claude) was used during the development of this framework for equation structuring, literature synthesis, and parts of the numerical coding. All scientific decisions, parameter choices, and interpretations are entirely the author's own. Preprint submitted to Physical Review E.email:[email protected]