Atomic surface mobility of glasses plays an important role in understanding glass dynamics and determining many fundamental processes on the surface.However,the diffusion dynamics at the free surface in marginal glass...Atomic surface mobility of glasses plays an important role in understanding glass dynamics and determining many fundamental processes on the surface.However,the diffusion dynamics at the free surface in marginal glasses remains unknown due to limited glass formation ability.In this study,we systematically investigate surface diffusion and relaxation behavior in four marginal glass-forming Fe-based metallic glasses with great application potential.Surface diffusion rates in marginal glassforming Fe-based metallic glasses are significantly faster than those of stable metallic glasses.For the first time,an abnormal β_(t) relaxation mode with thermal activation character is identified betweenαandβrelaxation.Strikingly,the activation energy of surface diffusion matches that ofβt relaxation.A mechanism involving cooperative cluster motion associated withβt relaxation is proposed to explain the ultrafast surface diffusion.These results establish a direct correlation between surface diffusion and bulk relaxation,providing a basis for tailoring surface properties in metallic glasses.展开更多
基金supported by the National Key R&D Program of China(Grant No.2024YFB3813700)the National Natural Science Foundation of China(Grant Nos.52471187,52201194,52222105,92163108,and 52231006)+2 种基金3315 Innovation Youth Talent in Ningbo City(Grant No.2021A123G)the Zhejiang Provincial Natural Science Foundation of China(Grant No.LZY23E010002)the Natural Science Foundation of Ningbo City(Grant No.2023J342).
文摘Atomic surface mobility of glasses plays an important role in understanding glass dynamics and determining many fundamental processes on the surface.However,the diffusion dynamics at the free surface in marginal glasses remains unknown due to limited glass formation ability.In this study,we systematically investigate surface diffusion and relaxation behavior in four marginal glass-forming Fe-based metallic glasses with great application potential.Surface diffusion rates in marginal glassforming Fe-based metallic glasses are significantly faster than those of stable metallic glasses.For the first time,an abnormal β_(t) relaxation mode with thermal activation character is identified betweenαandβrelaxation.Strikingly,the activation energy of surface diffusion matches that ofβt relaxation.A mechanism involving cooperative cluster motion associated withβt relaxation is proposed to explain the ultrafast surface diffusion.These results establish a direct correlation between surface diffusion and bulk relaxation,providing a basis for tailoring surface properties in metallic glasses.
