A mathematical model for the three-dimensional simulation of free dendritic growth and microstructure evolutionwas developed based on the growth mechanism of crystal grains and basic transfer equations such as heat, m...A mathematical model for the three-dimensional simulation of free dendritic growth and microstructure evolutionwas developed based on the growth mechanism of crystal grains and basic transfer equations such as heat, massand momentum transfer equations. Many factors including constitutional undercooling, curvature undercooling andanisotropy, which had vital influences on the microstructure evolution, were considered in the model. Simulated resultsshowed that final microstructural patterns and free dendritic growth could be predicted reasonably and calculatedresults were coincident with experimental The simulated results of free dendritic growth indicated that the strength ofanisotropy has significant effects on free dendritic growth, dendrite profile, micro solute and temperature distribution.The dendritic grain profiles with fully-grown parallel secondary arm tend to be formed at the intensive anisotropy,while near octahedral grain profiles with small protuberances of surface at low strength of anisotropy. The simulatedresults of free dendritic growth also indicated that there are small molten pools left in interdendritic areas. This ishelpful to understand the fundamental of the formation of microstructure related defects such as microsegregationand microporosity.展开更多
基金The work was sponsored by the Significant Project of National Natural Science Foundation of China(No.59990470-3), the National Significant Fundamental Research Project of the Ministry of Science and Technology of China(No. G2000067208-3) and the Fundamental Research Project of Tsinghua University.
文摘A mathematical model for the three-dimensional simulation of free dendritic growth and microstructure evolutionwas developed based on the growth mechanism of crystal grains and basic transfer equations such as heat, massand momentum transfer equations. Many factors including constitutional undercooling, curvature undercooling andanisotropy, which had vital influences on the microstructure evolution, were considered in the model. Simulated resultsshowed that final microstructural patterns and free dendritic growth could be predicted reasonably and calculatedresults were coincident with experimental The simulated results of free dendritic growth indicated that the strength ofanisotropy has significant effects on free dendritic growth, dendrite profile, micro solute and temperature distribution.The dendritic grain profiles with fully-grown parallel secondary arm tend to be formed at the intensive anisotropy,while near octahedral grain profiles with small protuberances of surface at low strength of anisotropy. The simulatedresults of free dendritic growth also indicated that there are small molten pools left in interdendritic areas. This ishelpful to understand the fundamental of the formation of microstructure related defects such as microsegregationand microporosity.
