Pre-melting is a phenomenon that below the melting point the liquid-like structure appears at the grainboundary while the grain interior remains a crystal structure. The phase-field crystal method was employed to inve...Pre-melting is a phenomenon that below the melting point the liquid-like structure appears at the grainboundary while the grain interior remains a crystal structure. The phase-field crystal method was employed to investigate the early evolution of the liquid pools in pre-melting regions, mainly involving four structural transformations: solid-solid state → small droplet → large liquid pool → homogeneous liquid melting. The microscopic morphology and free energy variation with different average atomic densities demonstrate that the average atomic density is sensitive to the morphological characteristics of liquid pools. Both two-dimensional and three-dimensional simulation results show that the amplitude reduction of order parameters can promote the order-disorder transition of grain boundaries, causing pre-melting in the edge dislocation aggregation. The relationship between the average atomic density and the width of the liquid pools is verified from thermodynamics, which provides a prerequisite for the application of high-temperature strain in the later stage to some extent.展开更多
Drift velocity is a very important paramcter for predictirg the pool volumetric void fraction. Two-phase system of gas and high viscous liquids pool is encountered in various engineering applications. A review of the ...Drift velocity is a very important paramcter for predictirg the pool volumetric void fraction. Two-phase system of gas and high viscous liquids pool is encountered in various engineering applications. A review of the literature shows no data for explaining the effect of highly viscous liquids on the drift velocity. This paper’s analysis shows that there is a considerable influence. It is shown that the foaming behaviour of liquids is dependent on the surface properties. For some highly viscous liquids at a given superficial gas velocity, the viscosity changes with time. The effect of "foam" and "time" on drift velocity is clearly elucidated.展开更多
Based on the three-dimensional model of TIG weld pool established,the effect of the arc force on liquid surface was investigated.The simulation was carried out with finite elements software Surface Evolver.The influen...Based on the three-dimensional model of TIG weld pool established,the effect of the arc force on liquid surface was investigated.The simulation was carried out with finite elements software Surface Evolver.The influence of the arc force on the weld pool shape was also studied.According to the results,the variation of the weld shape and the parameters with different arc force strength was obtained.Compared with the back weld pool,the top weld pool was influenced more strongly by the arc force.These results provide an effective basis for further study of the TIG weld pool.展开更多
基金supported by the National Natural Science Foundation of China (51774254,51774253,51701187,51674226,51804279,51801189)The Science and Technology Major Project of Shanxi Province,China (20191102008)+2 种基金Platform and Talent Project of Shanxi Province,China (201805D211036)Guiding Local Science and Technology Development Projects by the Central Government of China (YDZX20191400002796)Transformation of Scientific and Technological Achievements Special Guide Project of Shanxi Province,China (201804D131039)。
文摘Pre-melting is a phenomenon that below the melting point the liquid-like structure appears at the grainboundary while the grain interior remains a crystal structure. The phase-field crystal method was employed to investigate the early evolution of the liquid pools in pre-melting regions, mainly involving four structural transformations: solid-solid state → small droplet → large liquid pool → homogeneous liquid melting. The microscopic morphology and free energy variation with different average atomic densities demonstrate that the average atomic density is sensitive to the morphological characteristics of liquid pools. Both two-dimensional and three-dimensional simulation results show that the amplitude reduction of order parameters can promote the order-disorder transition of grain boundaries, causing pre-melting in the edge dislocation aggregation. The relationship between the average atomic density and the width of the liquid pools is verified from thermodynamics, which provides a prerequisite for the application of high-temperature strain in the later stage to some extent.
文摘Drift velocity is a very important paramcter for predictirg the pool volumetric void fraction. Two-phase system of gas and high viscous liquids pool is encountered in various engineering applications. A review of the literature shows no data for explaining the effect of highly viscous liquids on the drift velocity. This paper’s analysis shows that there is a considerable influence. It is shown that the foaming behaviour of liquids is dependent on the surface properties. For some highly viscous liquids at a given superficial gas velocity, the viscosity changes with time. The effect of "foam" and "time" on drift velocity is clearly elucidated.
文摘Based on the three-dimensional model of TIG weld pool established,the effect of the arc force on liquid surface was investigated.The simulation was carried out with finite elements software Surface Evolver.The influence of the arc force on the weld pool shape was also studied.According to the results,the variation of the weld shape and the parameters with different arc force strength was obtained.Compared with the back weld pool,the top weld pool was influenced more strongly by the arc force.These results provide an effective basis for further study of the TIG weld pool.
