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

PT Li and RH Zhang and YT Song and ZY Ding and N Jin and MY Hu and Y Liu and R Hu, MATERIALS TODAY COMMUNICATIONS, 49, 113962 (2025).

DOI: 10.1016/j.mtcomm.2025.113962

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 similar to 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.

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