Strengthening mechanism of polycrystal AuPt alloys during nanoindentation

Q Liu and YY Tian and CY Du and SY Chen and GJ Luo, MATERIALS CHEMISTRY AND PHYSICS, 334, 130464 (2025).

DOI: 10.1016/j.matchemphys.2025.130464

The strengthening mechanisms of the polycrystal AuPt alloys with homogeneous composition have been revealed in this work. The effects of the temperature and composition ratio on the nanoindentation behavior of AuPt alloys are investigated by molecular dynamics (MD) simulations. At 77K, the superior hardness of polycrystal AuPt alloys is ascribed to the combined impact of twin boundary (TB) strengthening and the work hardening triggered by the high dislocation density. As the Au content increases, the plastic deformation mechanism of polycrystal AuPt alloy transitions from being predominantly influenced by the grain boundary (GB) damage to being primarily directed by the dislocation motion. Polycrystal AuPt alloy with 73 % Au and 27 % Pt exhibits the elevated hardness coupled with excellent plasticity, owing to the active dislocation motion and the high dislocation density observed during plastic deformation. These results offer significant information for the engineering of the advanced materials with excellent mechanical properties, while also providing a theoretical guidance for the enhancement of aerospace materials meant to operate in extreme conditions.

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