Development of an electrocatalyst that is cheap and has good properties to replace conventional noble metals is important for H_(2) applications.In this study,dealloying of an amorphous Ti_(37)Cu_(60)Ru_(3) alloy was ...Development of an electrocatalyst that is cheap and has good properties to replace conventional noble metals is important for H_(2) applications.In this study,dealloying of an amorphous Ti_(37)Cu_(60)Ru_(3) alloy was performed to prepare a freestanding nanostructured hydrogen evolution reaction(HER)catalyst.The effect of dealloying and addition of Ru to TiCu alloys on the microstructure and HER properties under alkaline conditions was investigated.3 at.%Ru addition in Ti_(40)Cu_(60) decreases the overpotential to reach a current density of 10mA cm^(-2) and Tafel slope of the dealloyed samples to 35 and 34mV dec−1.The improvement of electrocatalytic properties was attributed to the formation of a nanostructure and the modification of the electronic structure of the catalyst.First-principles calculations based on density function theory indicate that Ru decreases the Gibbs free energy of water dissociation.This work presents a method to prepare an efficient electrocatalyst via dealloying of amorphous alloys.展开更多
Metallic glasses(MGs)have an amorphous atomic arrangement,but their structure and dynamics in the nanoscale are not homogeneous.Numerous studies have confirmed that the static and dynamic heterogeneities of MGs are vi...Metallic glasses(MGs)have an amorphous atomic arrangement,but their structure and dynamics in the nanoscale are not homogeneous.Numerous studies have confirmed that the static and dynamic heterogeneities of MGs are vital for their deformation mechanism.The“defects”in MGs are envisaged to be structurally loosely packed and dynamically active to external stimuli.To date,no definite structure-property relationship has been established to identify liquid-like“defects”in MGs.In this paper,we proposed a machine-learned“defects”from atomic trajectories rather than static structural signatures.We analyzed the atomic motion behavior at different temperatures via a k-nearest neighbors machine learning model,and quantified the dynamics of individual atoms as the machine-learned temperature.Applying this new temperature-like parameter to MGs under stress-induced flow,we can recognize which atoms respond like“liquids”to the applied loads.The evolution of liquid-like regions reveals the dynamic origin of plasticity(thermo-and acousto-plasticity)of MGs and the correlation between stress-induced heterogeneity and local environment around atoms,providing new insights into thermo-and acousto-plastic forming.展开更多
60NiTi alloy is considered to be a promising material for specialized bearing and gear applications due to its high hardness,strength,and low modulus.However,fabricating 60NiTi through conventional processing methods ...60NiTi alloy is considered to be a promising material for specialized bearing and gear applications due to its high hardness,strength,and low modulus.However,fabricating 60NiTi through conventional processing methods is challenging due to the brittleness and poor workability.In this study,60NiTi with high relative density was successfully fabricated directly from pre-alloyed powder through hot isostatic pressing.The effects of solution and aging treatments on microstructure and mechanical properties were systematically studied by advanced characterization techniques.The hot-isostatic-pressed 60NiTi showed low average hardness and elastic strain due to the formation of a soft Ni_(3)Ti phase and B2 NiTi matrix.Solution treatment above 1000℃dissolved the Ni_(3)Ti phase and promoted the formation of nanoscale Ni_(4)Ti_(3)precipitates,which significantly improved the hardness,strength,and elastic strain of 60NiTi.The formation of the Ni_(4)Ti_(3) phase can be mainly attributed to the driving forces induced by the chemical supersaturation and mechanical stress concentration.Finally,the phase transformation mechanisms during heat treatment and compression test were discussed.展开更多
基金National Natural Science Foundation of China,Grant/Award Number:52071217。
文摘Development of an electrocatalyst that is cheap and has good properties to replace conventional noble metals is important for H_(2) applications.In this study,dealloying of an amorphous Ti_(37)Cu_(60)Ru_(3) alloy was performed to prepare a freestanding nanostructured hydrogen evolution reaction(HER)catalyst.The effect of dealloying and addition of Ru to TiCu alloys on the microstructure and HER properties under alkaline conditions was investigated.3 at.%Ru addition in Ti_(40)Cu_(60) decreases the overpotential to reach a current density of 10mA cm^(-2) and Tafel slope of the dealloyed samples to 35 and 34mV dec−1.The improvement of electrocatalytic properties was attributed to the formation of a nanostructure and the modification of the electronic structure of the catalyst.First-principles calculations based on density function theory indicate that Ru decreases the Gibbs free energy of water dissociation.This work presents a method to prepare an efficient electrocatalyst via dealloying of amorphous alloys.
基金supported by the National Natural Science Foundation of China(52071217)Guangdong Key Laboratory of Electromagnetic Control and Intelligent Robots。
文摘Metallic glasses(MGs)have an amorphous atomic arrangement,but their structure and dynamics in the nanoscale are not homogeneous.Numerous studies have confirmed that the static and dynamic heterogeneities of MGs are vital for their deformation mechanism.The“defects”in MGs are envisaged to be structurally loosely packed and dynamically active to external stimuli.To date,no definite structure-property relationship has been established to identify liquid-like“defects”in MGs.In this paper,we proposed a machine-learned“defects”from atomic trajectories rather than static structural signatures.We analyzed the atomic motion behavior at different temperatures via a k-nearest neighbors machine learning model,and quantified the dynamics of individual atoms as the machine-learned temperature.Applying this new temperature-like parameter to MGs under stress-induced flow,we can recognize which atoms respond like“liquids”to the applied loads.The evolution of liquid-like regions reveals the dynamic origin of plasticity(thermo-and acousto-plasticity)of MGs and the correlation between stress-induced heterogeneity and local environment around atoms,providing new insights into thermo-and acousto-plastic forming.
文摘60NiTi alloy is considered to be a promising material for specialized bearing and gear applications due to its high hardness,strength,and low modulus.However,fabricating 60NiTi through conventional processing methods is challenging due to the brittleness and poor workability.In this study,60NiTi with high relative density was successfully fabricated directly from pre-alloyed powder through hot isostatic pressing.The effects of solution and aging treatments on microstructure and mechanical properties were systematically studied by advanced characterization techniques.The hot-isostatic-pressed 60NiTi showed low average hardness and elastic strain due to the formation of a soft Ni_(3)Ti phase and B2 NiTi matrix.Solution treatment above 1000℃dissolved the Ni_(3)Ti phase and promoted the formation of nanoscale Ni_(4)Ti_(3)precipitates,which significantly improved the hardness,strength,and elastic strain of 60NiTi.The formation of the Ni_(4)Ti_(3) phase can be mainly attributed to the driving forces induced by the chemical supersaturation and mechanical stress concentration.Finally,the phase transformation mechanisms during heat treatment and compression test were discussed.
