Unveiling temperature-driven deformation mechanisms in AuPt₂₀ nano-polycrystalline alloys through integrated molecular dynamics and experimental analysis

As a critical material for detection applications, the AuPt₂₀ alloy is valued for its exceptionally low magnetic susceptibility, yet its high cost has limited comprehensive studies. By combining molecular dynamics (MD) simulations with experimental techniques, this study introduces a novel, cost-effective approach to elucidate the temperature-dependent deformation mechanisms of AuPt₂₀ nano-polycrystalline (NPC) alloys. For the first time, we achieved decimeter-scale preparation of AuPt₂₀ alloy, enabling detailed microstructural analysis. Scanning electron microscopy and transmission electron microscopy revealed a substitutional solid solution with equiaxed grains as the alloy's defining feature. The experimental findings guided MD simulations to explore deformation behavior across a temperature range, with comparative analyses of Au and Pt NPC alloys. Our results demonstrate that temperature has a profound influence on deformation mechanisms. Below 600 K, deformation in Au NPC alloys is governed by a critical grain size of ∼7.59 nm, while in AuPt₂₀ NPC alloys, dislocation motion dominates in grains smaller than this threshold. At strains exceeding 10.0 %, severe plastic deformation occurs across nearly all grains. At higher temperatures (≥600 K), the deformation mechanism shifts from dislocation-driven plasticity to grain boundary sliding and recrystallization, marking a significant transition. These findings provide critical insights for designing advanced AuPt-based alloys for applications such as gravitational wave detectors.