The preparation and solidification of metallic droplets attract more and more attention for their signifi cance in both engineering and scientifi c fi elds. In this paper, the preparation and characterization of Snbas...The preparation and solidification of metallic droplets attract more and more attention for their signifi cance in both engineering and scientifi c fi elds. In this paper, the preparation and characterization of Snbased alloy droplets using different methods such as atomization and consumable electrode direct current arc(CDCA) technique are reviewed. The morphology and structure of these droplets were determined by optical microscopy, X-ray diffraction(XRD) and scanning electron microscopy(SEM). The solidifi cation behavior of single droplet was systematically studied by means of scanning calorimetry(DSC), and the nucleation kinetics was also calculated. In particular, the development of fast scanning calorimetry(FSC) made it possible to investigate the evolution of undercooling under ultrafast but controllable heating and cooling conditions. The combination of CDCA technique and FSC measurements opens up a new door for quantitative studies on droplet solidifi cation, which is accessible to demonstrate some theories by experiments.展开更多
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
基金supported by the National Natural Science Foundation of China(Grant Nos.51171105 and 50971086)the Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learningthe 085 project in Shanghai University
文摘The preparation and solidification of metallic droplets attract more and more attention for their signifi cance in both engineering and scientifi c fi elds. In this paper, the preparation and characterization of Snbased alloy droplets using different methods such as atomization and consumable electrode direct current arc(CDCA) technique are reviewed. The morphology and structure of these droplets were determined by optical microscopy, X-ray diffraction(XRD) and scanning electron microscopy(SEM). The solidifi cation behavior of single droplet was systematically studied by means of scanning calorimetry(DSC), and the nucleation kinetics was also calculated. In particular, the development of fast scanning calorimetry(FSC) made it possible to investigate the evolution of undercooling under ultrafast but controllable heating and cooling conditions. The combination of CDCA technique and FSC measurements opens up a new door for quantitative studies on droplet solidifi cation, which is accessible to demonstrate some theories by experiments.
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.
