摘要
为了研究二元组分铸锭中通道偏析的形成和发展,建立了双扩散作用下糊状区液相流动与溶质分布的数学模型,并对铸锭定向凝固过程中的通道偏析进行了数值模拟。运用SIMPLE算法编制了求解数学模型的程序,对模型中的质量、动量、能量和溶质等守恒方程联立求解。通过对NH4Cl-H2O铸锭底面冷却、凝固过程进行模拟研究,得到了定向凝固过程中的温度场、流场、溶质场。铸锭底面冷却时,富含溶质的枝晶间液相的流动可形成垂直向上生长的偏析通道,一些偏析通道由于相连通道的优先生长导致溶质贫化而被掩埋。通道的形成与溶质质量分数C0有很大关系,C0越高,越容易形成通道。C0较低的铸锭,只有在溶质富集到一定程度后才会产生通道。
The evolution of channel segregation in a binary alloy for various initial species concentrations in the ingot was analyzed using a mathematical model describing the fluid flow and species distributions in the mushy zone in a directionally solidified ingot. The model used the SIMPLE algorithm to simultaneously solve the quality, momentum, energy, and species conservation equations. The temperature, fluid flow, and species concentration distributions during the directional solidification were obtained for a NH4Cl-H2O ingot cooled from the bottom. The segregated channels grew upwards due to the movement of the water-rich interdendritic fluid, some of which may be buried in regions of low species concentrations when the growth in other regions is faster. The channel formation is related to the initial species concentration. Higher species concentrations are more likely to form channels. For low initial concentrations, channels will form at the end of the solidification stage when the species concentrations are high enough.
出处
《清华大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2003年第11期1444-1447,共4页
Journal of Tsinghua University(Science and Technology)
基金
国家自然科学基金
宝钢联合基金资助项目(50174031)
