Fragility is one of the central concepts in glass and liquid sciences,as it characterizes the extent of deviation of viscosity from Arrhenius behavior and is linked to a range of glass properties.However,the intervent...Fragility is one of the central concepts in glass and liquid sciences,as it characterizes the extent of deviation of viscosity from Arrhenius behavior and is linked to a range of glass properties.However,the intervention of crystallization often prevents the assessment of fragility in poor glass-formers,such as supercooled metallic liquids.Hence experimental data on their compositional dependence are scarce,let alone fundamentally understood.In this work,we use fast scanning calorimetry to overcome this obstacle and systematically study the fragility in a ternary La–Ni–Al system,over previously inaccessible composition space.We observe fragility dropped in a small range with the Al alloying,indicating an alloying-induced fragility crossover.We use x-ray photoelectron spectroscopy,resistance measurements,electronic structure calculations,and DFT-based deep-learning atomic simulations to investigate the cause of this fragility drop.These results show that the fragility crossover can be fundamentally ascribed to the electronic covalency associated with the unique Al–Al interactions.Our findings provide insight into the origin of fragility in metallic liquids from an electronic structure perspective and pave a new way for the design of metallic glasses.展开更多
The stability of glass against crystallization is of importance in practical applications and theoretical understanding of the nature of glass materials.Annealing has complicated influences on glass stability.It induc...The stability of glass against crystallization is of importance in practical applications and theoretical understanding of the nature of glass materials.Annealing has complicated influences on glass stability.It induces either delayed or early crystallization,depending on detailed protocols and specific materials.By interrogating the thermal behaviors of twelve metallic glasses(MGs),we find that enhanced stability is correlated to another process:the so-called shadow glass transition and its evolution.Delayed crystallization can be observed when the shadow glass transition is shifted to cross the temperature of crystallization.Concurrently,the shadow glass transition evolves to an enthalpy overshoot.Molecular dynamics simulations support these findings and suggest that the suppressed string-like motion,relating to the shadow glass transition and the enthalpy overshoot,is likely the origin of the postponed nucleation ordering and enhanced glass stability.展开更多
基金National Thousand Young Talents Program of China,and the National Natural Science Foundation of China(NSFC 52201180).
文摘Fragility is one of the central concepts in glass and liquid sciences,as it characterizes the extent of deviation of viscosity from Arrhenius behavior and is linked to a range of glass properties.However,the intervention of crystallization often prevents the assessment of fragility in poor glass-formers,such as supercooled metallic liquids.Hence experimental data on their compositional dependence are scarce,let alone fundamentally understood.In this work,we use fast scanning calorimetry to overcome this obstacle and systematically study the fragility in a ternary La–Ni–Al system,over previously inaccessible composition space.We observe fragility dropped in a small range with the Al alloying,indicating an alloying-induced fragility crossover.We use x-ray photoelectron spectroscopy,resistance measurements,electronic structure calculations,and DFT-based deep-learning atomic simulations to investigate the cause of this fragility drop.These results show that the fragility crossover can be fundamentally ascribed to the electronic covalency associated with the unique Al–Al interactions.Our findings provide insight into the origin of fragility in metallic liquids from an electronic structure perspective and pave a new way for the design of metallic glasses.
基金supported by the National Thousand Young Talents Program of China,the National Natural Science Foundation of China(52071147 and 52201180)the China Postdoctoral Science Foundation(2023T160241 and2023M731176)S.W.thanks the support of Novo Nordisk Foundation(NNF21OC0071257)
文摘The stability of glass against crystallization is of importance in practical applications and theoretical understanding of the nature of glass materials.Annealing has complicated influences on glass stability.It induces either delayed or early crystallization,depending on detailed protocols and specific materials.By interrogating the thermal behaviors of twelve metallic glasses(MGs),we find that enhanced stability is correlated to another process:the so-called shadow glass transition and its evolution.Delayed crystallization can be observed when the shadow glass transition is shifted to cross the temperature of crystallization.Concurrently,the shadow glass transition evolves to an enthalpy overshoot.Molecular dynamics simulations support these findings and suggest that the suppressed string-like motion,relating to the shadow glass transition and the enthalpy overshoot,is likely the origin of the postponed nucleation ordering and enhanced glass stability.
