The morphological stability of a planar interface with different crystallographic orientations is studied under a small positive temperature gradient using a transparent model alloy of succinonitrile. Novel experiment...The morphological stability of a planar interface with different crystallographic orientations is studied under a small positive temperature gradient using a transparent model alloy of succinonitrile. Novel experimental apparatus is constructed to provide a temperature gradient of about 0.37 K/mm. Under this small temperature gradient, the planar interface instability depends largely on the crystallographic orientation. It is shown experimentally that the effect of interfacial energy anisotropy on planar interface stability cannot be neglected even in a small temperature gradient system. Higher interfacial energy anisotropy leads the planar interface to become more unstable, which is different from the stabilizing effect of the interfacial energy on the planar interface. The experimental results are in agreement with previous theoretical calculations and phase field simulations.展开更多
Based on the models of hydrate phase equilibrium in bulk water and porous media,an improved model was proposed to predict the methane hydrate equilibrium in marine sediment environment.In the suggested model,mechanica...Based on the models of hydrate phase equilibrium in bulk water and porous media,an improved model was proposed to predict the methane hydrate equilibrium in marine sediment environment.In the suggested model,mechanical equilibrium of force between the interfaces in hydrate-liquid-vapor system was considered.When electrolyte was present in pore water,interfacial energy between hydrate and liquid was corrected by an equation that is expressed as the function of temperature and electrolyte concentration.The activity of water is calculated based on the Pitzer model and the interfacial energy between liquid and gas is solved using the Li method.The prediction results show good agreement with the experimental data.By comparison with other models,it is proved that this model can improve the accuracy for predicting hydrate phase equilibrium in marine sediment environment.展开更多
Interfacial energy anisotropy plays an important role in tilted growth of eutectics. However, previous studies mainly focused on the solid-solid interface energy anisotropy, and whether the solid-liquid interface ener...Interfacial energy anisotropy plays an important role in tilted growth of eutectics. However, previous studies mainly focused on the solid-solid interface energy anisotropy, and whether the solid-liquid interface energy anisotropy can significantly affect the tilted growth of eutectics still remains unclear. In this study, a multi-phase field model is employed to investigate both the effect of solid-liquid interfacial energy anisotropy and the effect of solid-solid interfacial energy anisotropy on tilted growth of eutectics. The findings reveal that both the solid-liquid interfacial energy anisotropy and the solid-solid interfacial energy anisotropy can induce the tilted growth of eutectics. The results also demonstrate that when the rotation angle is within a range of 30°-60°, the growth of tilted eutectics is governed jointly by the solid-solid interfacial energy anisotropy and the solid-liquid interfacial energy anisotropy;otherwise, it is mainly controlled by the solid-solid interfacial energy anisotropy. Further analysis shows that the unequal pinning angle at triple point caused by the adjustment of the force balance results in different solute-diffusion rates on both sides of triple point. This will further induce an asymmetrical concentration distribution along the pulling direction near the solid-liquid interface and the tilted growth of eutectics. Our findings not only shed light on the formation mechanism of tilted eutectics but also provide theoretical guidance for controlling the microstructure evolution during eutectic solidification.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 50971102 and 50901061)the National Basic Research Program of China (Grant No. 2011CB610402)+2 种基金the Fund of the State Key Laboratory of Solidification Processing in Northwestern Polytechnical University,China (Grant Nos. 02-TZ-2008 and 36-TP-2009)the Programme of Introducing Talents of Discipline to Universities,China (Grant No. 08040)the National Science Foundation for Post-doctoral Scientists of China(Grant No. 20110491689)
文摘The morphological stability of a planar interface with different crystallographic orientations is studied under a small positive temperature gradient using a transparent model alloy of succinonitrile. Novel experimental apparatus is constructed to provide a temperature gradient of about 0.37 K/mm. Under this small temperature gradient, the planar interface instability depends largely on the crystallographic orientation. It is shown experimentally that the effect of interfacial energy anisotropy on planar interface stability cannot be neglected even in a small temperature gradient system. Higher interfacial energy anisotropy leads the planar interface to become more unstable, which is different from the stabilizing effect of the interfacial energy on the planar interface. The experimental results are in agreement with previous theoretical calculations and phase field simulations.
基金supported by the Key program of National Natural Science Foundation of China (50736001)the High-tech Research and Development Program of China (2006AA09A209-5)the Major State Basic Research Development Program of China (2009CB219507)
文摘Based on the models of hydrate phase equilibrium in bulk water and porous media,an improved model was proposed to predict the methane hydrate equilibrium in marine sediment environment.In the suggested model,mechanical equilibrium of force between the interfaces in hydrate-liquid-vapor system was considered.When electrolyte was present in pore water,interfacial energy between hydrate and liquid was corrected by an equation that is expressed as the function of temperature and electrolyte concentration.The activity of water is calculated based on the Pitzer model and the interfacial energy between liquid and gas is solved using the Li method.The prediction results show good agreement with the experimental data.By comparison with other models,it is proved that this model can improve the accuracy for predicting hydrate phase equilibrium in marine sediment environment.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 51871183 and 51571165)。
文摘Interfacial energy anisotropy plays an important role in tilted growth of eutectics. However, previous studies mainly focused on the solid-solid interface energy anisotropy, and whether the solid-liquid interface energy anisotropy can significantly affect the tilted growth of eutectics still remains unclear. In this study, a multi-phase field model is employed to investigate both the effect of solid-liquid interfacial energy anisotropy and the effect of solid-solid interfacial energy anisotropy on tilted growth of eutectics. The findings reveal that both the solid-liquid interfacial energy anisotropy and the solid-solid interfacial energy anisotropy can induce the tilted growth of eutectics. The results also demonstrate that when the rotation angle is within a range of 30°-60°, the growth of tilted eutectics is governed jointly by the solid-solid interfacial energy anisotropy and the solid-liquid interfacial energy anisotropy;otherwise, it is mainly controlled by the solid-solid interfacial energy anisotropy. Further analysis shows that the unequal pinning angle at triple point caused by the adjustment of the force balance results in different solute-diffusion rates on both sides of triple point. This will further induce an asymmetrical concentration distribution along the pulling direction near the solid-liquid interface and the tilted growth of eutectics. Our findings not only shed light on the formation mechanism of tilted eutectics but also provide theoretical guidance for controlling the microstructure evolution during eutectic solidification.
