The role of grain-boundary (GB) in the melting for Sigma=5 bicrystals of B2 NiAl is investigated by molecular-dynamics simulation. The thermodynamic properties of the boundary are monitored over a wide temperature ran...The role of grain-boundary (GB) in the melting for Sigma=5 bicrystals of B2 NiAl is investigated by molecular-dynamics simulation. The thermodynamic properties of the boundary are monitored over a wide temperature range including the thermodynamic melting point T-m which is determined by using a many-body potential fitted to NiAl. A thermal disorder transition in the GB region occurs well below the melting point. Our results indicate that such a transition is a continuous process and there is no evidence of premelting, which is entirely in accord with experimental results and theoretical prediction. Moreover, we also find that the superheated temperature range of this intermetallic alloy is much wider than that of some elemental metals.展开更多
The present paper summarizes the current status of high resolution elect;on microscopy ( HREM) and the applications of HREM to materials science and condensed matter physics. This review recounts the latest developmen...The present paper summarizes the current status of high resolution elect;on microscopy ( HREM) and the applications of HREM to materials science and condensed matter physics. This review recounts the latest development of high resolution electron microscope, progress of HREM and the applications of HREM, including the crystal structure determination of microcrystalline materials and characterization of the local structure of the defects and nanostructured materials as well as qualitative and quantitative analysis of the grain boundaries, interfaces and interfacial reactions in the advanced materials by means of HREM in combination with electron diffraction, subnanometer level analysis, image simulation and image processing.展开更多
文摘The role of grain-boundary (GB) in the melting for Sigma=5 bicrystals of B2 NiAl is investigated by molecular-dynamics simulation. The thermodynamic properties of the boundary are monitored over a wide temperature range including the thermodynamic melting point T-m which is determined by using a many-body potential fitted to NiAl. A thermal disorder transition in the GB region occurs well below the melting point. Our results indicate that such a transition is a continuous process and there is no evidence of premelting, which is entirely in accord with experimental results and theoretical prediction. Moreover, we also find that the superheated temperature range of this intermetallic alloy is much wider than that of some elemental metals.
文摘The present paper summarizes the current status of high resolution elect;on microscopy ( HREM) and the applications of HREM to materials science and condensed matter physics. This review recounts the latest development of high resolution electron microscope, progress of HREM and the applications of HREM, including the crystal structure determination of microcrystalline materials and characterization of the local structure of the defects and nanostructured materials as well as qualitative and quantitative analysis of the grain boundaries, interfaces and interfacial reactions in the advanced materials by means of HREM in combination with electron diffraction, subnanometer level analysis, image simulation and image processing.
