Elements(As,Bi)and(Cu,Fe)exhibiting two typical segregation behavior in liquid Sb alloys were selected as solute atoms for analysis.Ab initio molecular dynamics(AIMD)simulations were employed to study the molten Sb al...Elements(As,Bi)and(Cu,Fe)exhibiting two typical segregation behavior in liquid Sb alloys were selected as solute atoms for analysis.Ab initio molecular dynamics(AIMD)simulations were employed to study the molten Sb alloy at different temperatures.By analyzing its pair correlation function(PCF),bond pairs,bond angle distribution function(BADF),and Voronoi polyhedron(VP),the short-range order(SRO)of the alloy was investigated.In the Sb melt,the solute atoms Cu and Fe,which have smaller distribution coefficients,exhibit a stronger affinity for Sb than the solute atoms As and Bi,which have larger distribution coefficients.The BADF of As and Bi with larger distribution coefficients shows a lower probability of small-angle peaks compared to large-angle peaks,whereas the BADF of Cu and Fe with smaller distribution coefficients exhibits the opposite trend.The BADF reveals that Sb-As and Sb-Bi approach pure Sb melt,while Sb-Cu and Sb-Fe deviate significantly.Compared to Sb-Cu and Sb-Fe,the Sb-As and Sb-Bi systems exhibit more low-index bonds,suggesting weaker interactions and more disorder.The VP fractions around As and Bi atoms are lower than those around Cu and Fe,and the VP face distributions around As and Bi are more complex.There are differences in the VP around different solute atoms,primarily due to the varying bond pair fractions associated with each solute atom.Fe has the smallest diffusion coefficient,primarily due to its compact local structure.展开更多
A novel Ni_(30)Cr_(25)Al_(15)Co_(15)Mo_(5)Ti_(5)Y_(5) high-entropy alloy(HEA)coating was irradiated to optimize its internal structure via laser after supersonic particle deposition(SPD).Owing to the high energy densi...A novel Ni_(30)Cr_(25)Al_(15)Co_(15)Mo_(5)Ti_(5)Y_(5) high-entropy alloy(HEA)coating was irradiated to optimize its internal structure via laser after supersonic particle deposition(SPD).Owing to the high energy density of the laser and large temperature gradient,the crystallization process of the molecules and atoms in the coating was restrained and supercooling occurred.Experimental results showed that a considerable number of nano-crystal grains precipitated and amorphous structures were formed because of the random orientation of the crystals.The baseline of differential scanning calorimetry scans obtained for the coating started to shift at the Tg of 939.37℃ and a step was observed.Multiple dispersion peaks and lattice fringes indicated that the nucleation of the irradiated laser-induced topology optimized(LTO)coating was incomplete.The laser-induced topology optimizing treatment led to quasi-isotropy in the SPD coating.Furthermore,the LTO coating exhibited a residual stress of 18.4 MPa,stress-strain response,and fatigue limit of 265 MPa.Hence,the LTO coating exhibited higher performance than the unirradiated SPD coating.The Nyquist and Bode electrochemical impedance spectra of the LTO coating,including two relaxation processes,indicated that the corrosion process steadily recovered to the equilibrium state.This implies that the uniform oxidation passivation layer on the surface of the LTO coating insulated the material from the corrosive medium,protecting the substrate from further corrosion,thus enhancing the structural security of the material for use in super-intense laser facility applications.展开更多
The adsorption/desorption of OH*on electrode surfaces is pivotal in numerous electrocatalytic reactions.To understand the effect of electrolyte pH on that process,in this work,an advanced approach combining ab initio ...The adsorption/desorption of OH*on electrode surfaces is pivotal in numerous electrocatalytic reactions.To understand the effect of electrolyte pH on that process,in this work,an advanced approach combining ab initio molecular dynamics(AIMD)with free energy perturbation is employed to calculate the dehydrogenation free energy of water chemisorbed at differently electrified Pt(111)/electrolyte interfaces.Our findings reveal that the onset potential for OH*formation shifts negatively as the pH increases at low pH condition(pH<4.3),aligning with the cyclic voltammetry curves observed in experimental studies.It indicates the dissociation of chemisorbed water is the primary route for OH*adsorption at low pH condition.Furthermore,it is also found that the variation in dehydrogenation energy across different pH is primarily due to the local hydrogen bonding network surrounding the chemisorbed water.In addition,it is proposed that at high pH conditions OH-oxidation emerges as the primary route for OH*adsorption on Pt(111)constrained by the water chemisorption process.This work provides crucial insights into the pH-dependent adsorption behavior of OH*on the Pt(111)surface and aims to guide the optimization of electrolytes to boost the efficiency of related reactions.展开更多
文摘Elements(As,Bi)and(Cu,Fe)exhibiting two typical segregation behavior in liquid Sb alloys were selected as solute atoms for analysis.Ab initio molecular dynamics(AIMD)simulations were employed to study the molten Sb alloy at different temperatures.By analyzing its pair correlation function(PCF),bond pairs,bond angle distribution function(BADF),and Voronoi polyhedron(VP),the short-range order(SRO)of the alloy was investigated.In the Sb melt,the solute atoms Cu and Fe,which have smaller distribution coefficients,exhibit a stronger affinity for Sb than the solute atoms As and Bi,which have larger distribution coefficients.The BADF of As and Bi with larger distribution coefficients shows a lower probability of small-angle peaks compared to large-angle peaks,whereas the BADF of Cu and Fe with smaller distribution coefficients exhibits the opposite trend.The BADF reveals that Sb-As and Sb-Bi approach pure Sb melt,while Sb-Cu and Sb-Fe deviate significantly.Compared to Sb-Cu and Sb-Fe,the Sb-As and Sb-Bi systems exhibit more low-index bonds,suggesting weaker interactions and more disorder.The VP fractions around As and Bi atoms are lower than those around Cu and Fe,and the VP face distributions around As and Bi are more complex.There are differences in the VP around different solute atoms,primarily due to the varying bond pair fractions associated with each solute atom.Fe has the smallest diffusion coefficient,primarily due to its compact local structure.
基金supported by a grant from the Natural Science Foundation of Jiangsu Province (Grant No.BK20191036)the Foundation of Research Project of China (Grant No.JCKY 61420051911)。
文摘A novel Ni_(30)Cr_(25)Al_(15)Co_(15)Mo_(5)Ti_(5)Y_(5) high-entropy alloy(HEA)coating was irradiated to optimize its internal structure via laser after supersonic particle deposition(SPD).Owing to the high energy density of the laser and large temperature gradient,the crystallization process of the molecules and atoms in the coating was restrained and supercooling occurred.Experimental results showed that a considerable number of nano-crystal grains precipitated and amorphous structures were formed because of the random orientation of the crystals.The baseline of differential scanning calorimetry scans obtained for the coating started to shift at the Tg of 939.37℃ and a step was observed.Multiple dispersion peaks and lattice fringes indicated that the nucleation of the irradiated laser-induced topology optimized(LTO)coating was incomplete.The laser-induced topology optimizing treatment led to quasi-isotropy in the SPD coating.Furthermore,the LTO coating exhibited a residual stress of 18.4 MPa,stress-strain response,and fatigue limit of 265 MPa.Hence,the LTO coating exhibited higher performance than the unirradiated SPD coating.The Nyquist and Bode electrochemical impedance spectra of the LTO coating,including two relaxation processes,indicated that the corrosion process steadily recovered to the equilibrium state.This implies that the uniform oxidation passivation layer on the surface of the LTO coating insulated the material from the corrosive medium,protecting the substrate from further corrosion,thus enhancing the structural security of the material for use in super-intense laser facility applications.
基金support from the National Natural Science Foundation of China(Nos.22272193,22225302,21991151,and 21991150)the Ningbo Natural Science Foundation(No.2022J294)+1 种基金the Yongjiang Talent Introduction Program(No.2021A-115-G)Key Laboratory of Advanced Marine Materials,Ningbo Institute of Materials Technology and Engineering,Chinese Academy of Sciences,Ningbo.(No.2021A-115-G).
文摘The adsorption/desorption of OH*on electrode surfaces is pivotal in numerous electrocatalytic reactions.To understand the effect of electrolyte pH on that process,in this work,an advanced approach combining ab initio molecular dynamics(AIMD)with free energy perturbation is employed to calculate the dehydrogenation free energy of water chemisorbed at differently electrified Pt(111)/electrolyte interfaces.Our findings reveal that the onset potential for OH*formation shifts negatively as the pH increases at low pH condition(pH<4.3),aligning with the cyclic voltammetry curves observed in experimental studies.It indicates the dissociation of chemisorbed water is the primary route for OH*adsorption at low pH condition.Furthermore,it is also found that the variation in dehydrogenation energy across different pH is primarily due to the local hydrogen bonding network surrounding the chemisorbed water.In addition,it is proposed that at high pH conditions OH-oxidation emerges as the primary route for OH*adsorption on Pt(111)constrained by the water chemisorption process.This work provides crucial insights into the pH-dependent adsorption behavior of OH*on the Pt(111)surface and aims to guide the optimization of electrolytes to boost the efficiency of related reactions.
