Considering both the effect of nonisothermal nature of the solid/liquid interface and the microscopic solvability theory (MicST), a further improved version of free dendritic growth model for pure materials was propos...Considering both the effect of nonisothermal nature of the solid/liquid interface and the microscopic solvability theory (MicST), a further improved version of free dendritic growth model for pure materials was proposed. Model comparison indicates that there is a higher temperature at the tip of dendrite predicted by the present model compared with the corresponding model with the isothermal solid/liquid interface assumption. This is attributed to the sidewise thermal diffusion, i.e. the gradient of temperature along the nonisothermal interface. Furthermore, it is indicated that the distinction between the stability criteria from MicST and marginal stability theory (MarST) is more significant with the increase of bath undercoolings. Model test also indicates that the present model can give an agreement with the available experimental data. It is finally concluded that the nonisothermal nature of the solid/liquid interface and the stability criterion from MicST should be taken into account in modeling free dendritic growth.展开更多
A model has been developed for the calculation of the microstructural evolution in a rapidly directionally solidified immiscible alloy. Numerical solutions have been performed for Al Pb immiscible alloys. The results ...A model has been developed for the calculation of the microstructural evolution in a rapidly directionally solidified immiscible alloy. Numerical solutions have been performed for Al Pb immiscible alloys. The results demonstrate that at a higher solidification velocity a constitutional supercooling region appears in front of the solid/liquid interface and the liquid liquid decomposition takes place in this region. A higher solidification velocity leads to a higher nucleation rate and, therefore, a higher number density of the minority phase droplets. As a result, the average radius of droplets in the melt at the solid/liquid interface decreases with the solidification velocity.展开更多
利用与时间有关的瞬态形核理论计算了不同Nd含量的Al Fe V Si Nd合金中α Al相的形核率、形核孕育期与过冷度的关系 ,并计算了α Al形成非晶的临界冷却速率。结果表明 ,随Nd含量增加 ,合金的液相线温度提高 ,α Al形核孕育期延长 ,形核...利用与时间有关的瞬态形核理论计算了不同Nd含量的Al Fe V Si Nd合金中α Al相的形核率、形核孕育期与过冷度的关系 ,并计算了α Al形成非晶的临界冷却速率。结果表明 ,随Nd含量增加 ,合金的液相线温度提高 ,α Al形核孕育期延长 ,形核过冷度增加 ,形核率降低 ,临界冷却速率降低 ,从而增大其非晶的形成倾向。展开更多
基金Project(51671075) supported by the National Natural Science Foundation of ChinaProject(E201446) supported by the Natural Science Foundation of Heilongjiang Province,China+1 种基金Project(SKLSP201606) supported by Fund of the State Key Laboratory of Solidification Processing in NWPU,ChinaProject(2016M590970) supported by China Postdoctoral Science Foundation
文摘Considering both the effect of nonisothermal nature of the solid/liquid interface and the microscopic solvability theory (MicST), a further improved version of free dendritic growth model for pure materials was proposed. Model comparison indicates that there is a higher temperature at the tip of dendrite predicted by the present model compared with the corresponding model with the isothermal solid/liquid interface assumption. This is attributed to the sidewise thermal diffusion, i.e. the gradient of temperature along the nonisothermal interface. Furthermore, it is indicated that the distinction between the stability criteria from MicST and marginal stability theory (MarST) is more significant with the increase of bath undercoolings. Model test also indicates that the present model can give an agreement with the available experimental data. It is finally concluded that the nonisothermal nature of the solid/liquid interface and the stability criterion from MicST should be taken into account in modeling free dendritic growth.
文摘A model has been developed for the calculation of the microstructural evolution in a rapidly directionally solidified immiscible alloy. Numerical solutions have been performed for Al Pb immiscible alloys. The results demonstrate that at a higher solidification velocity a constitutional supercooling region appears in front of the solid/liquid interface and the liquid liquid decomposition takes place in this region. A higher solidification velocity leads to a higher nucleation rate and, therefore, a higher number density of the minority phase droplets. As a result, the average radius of droplets in the melt at the solid/liquid interface decreases with the solidification velocity.
