Characterizing immiscible metallic composites with electron microscopy and X-ray spectroscopy is the classic way of obtaining their structural and physical details.Nevertheless,such a combination lacks abil-ity to tel...Characterizing immiscible metallic composites with electron microscopy and X-ray spectroscopy is the classic way of obtaining their structural and physical details.Nevertheless,such a combination lacks abil-ity to tell the interfacial interactions at grain boundaries.Here we demonstrate a novel strategy to un-cover the mystery of interfacial interactions in such systems by spectroscopic microscopy.The morpho-logical and spectral data of samples were simultaneously recorded and analyzed,which reveals critical information regarding interfacial electronic modes.Taking W-Cu as a model,we experimentally quanti-fied its connectivity and unambiguously identified conditional bonding between W and Cu.Further,we chemically reconstructed the specific W-Cu boundary that possessed the strongest interactions and inves-tigated its atomic structure.The mechanism of W-Cu bonding was proposed and verified by first-principle calculations.The above methodology holds great promise to serve as a universal approach in achieving in-depth understanding of immiscible composites.展开更多
A model for describing solute segregation at grain boundaries has been developed for substitutional solid solution alloys,which integrates multiple factors from atomic to microstructural scales.A concept of mo-lar Gib...A model for describing solute segregation at grain boundaries has been developed for substitutional solid solution alloys,which integrates multiple factors from atomic to microstructural scales.A concept of mo-lar Gibbs free energy of segregation was introduced to evaluate the segregating capability of the solute elements in a closed system,through which the influences of grain boundary structure,grain size,ma-terial composition,and external conditions were described.Based on the evaluation of various energy forms related to solute segregation and grain growth processes,the nature of the thermal stabilization of nanograin structures by solute segregation was disclosed.A criterion for the destabilization of nanostruc-tures,which is determined by the competition of the change rates between the molar Gibbs free energy of segregation and the total energy of grain boundaries with grain size,has been proposed.This study provided guideline to achieve high-temperature stability of nanograin structures of solid solution alloys even for the weakly segregating nanocrystalline systems.展开更多
基金National Natural Science Foundation of China(No.52101032)to provide support for this work.F.T thanks the support from Beijing Natural Science Foun-dation(No.2214067).X.S.thanks the support from the National Natural Science Foundation of China(Nos.92163107,51621003).
文摘Characterizing immiscible metallic composites with electron microscopy and X-ray spectroscopy is the classic way of obtaining their structural and physical details.Nevertheless,such a combination lacks abil-ity to tell the interfacial interactions at grain boundaries.Here we demonstrate a novel strategy to un-cover the mystery of interfacial interactions in such systems by spectroscopic microscopy.The morpho-logical and spectral data of samples were simultaneously recorded and analyzed,which reveals critical information regarding interfacial electronic modes.Taking W-Cu as a model,we experimentally quanti-fied its connectivity and unambiguously identified conditional bonding between W and Cu.Further,we chemically reconstructed the specific W-Cu boundary that possessed the strongest interactions and inves-tigated its atomic structure.The mechanism of W-Cu bonding was proposed and verified by first-principle calculations.The above methodology holds great promise to serve as a universal approach in achieving in-depth understanding of immiscible composites.
基金supported by the Beijing Natural Science Foun-dation(No.2214067)the National Key R&D Program of China(Nos.2021YFB3501502 and 2021YFB3501504)the National Natural Science Foundation of China(No.92163107).
文摘A model for describing solute segregation at grain boundaries has been developed for substitutional solid solution alloys,which integrates multiple factors from atomic to microstructural scales.A concept of mo-lar Gibbs free energy of segregation was introduced to evaluate the segregating capability of the solute elements in a closed system,through which the influences of grain boundary structure,grain size,ma-terial composition,and external conditions were described.Based on the evaluation of various energy forms related to solute segregation and grain growth processes,the nature of the thermal stabilization of nanograin structures by solute segregation was disclosed.A criterion for the destabilization of nanostruc-tures,which is determined by the competition of the change rates between the molar Gibbs free energy of segregation and the total energy of grain boundaries with grain size,has been proposed.This study provided guideline to achieve high-temperature stability of nanograin structures of solid solution alloys even for the weakly segregating nanocrystalline systems.
