摘要
采用欧拉-欧拉法建立了稳恒磁场条件下描述过偏晶Al-Pb合金难混溶区凝固过程的数学模型,对过偏晶合金在有无磁场条件下的宏观偏析运动进行了数值模拟,研究了两相温度场、速度场、体积分数等物性参数对合金凝固显微组织演化的影响。结果表明,随着冷却过程的进行,有磁场作用下的温度场仍保持环形中心对称分布,有效的抑制了由于重力条件下较强的对流作用使中心高温区上移;速度场在磁场条件下为中心对称分布,因部分重力被抵消,Marangoni力的作用逐渐显现,速度明显降低且方向斜向下指向对称轴,凝固组织宏观偏析得到了有效的改善;磁场条件限制了L2项液滴的扩散长大和Ostwald熟化,同时有效限制了L2项液滴体积分数的增加,从而更有利于L2项液滴的均匀分布。
Euler-Eulerian Method was applied to establish a mathematical model that describes hypermonotectic Al-Pb alloys＇ solidification in the immiscible zone under the condition of static magnetic field. The numerical simulation of the macrosegregation motion of hypermonotectic alloys,with or without magnetic field,was conducted respectively. Influences of temperature field,velocity field and volume fraction on alloys＇ solidification microstructure evolution were studied. The results showed that with the process of cooling,temperature field still remaines symmetric distribution in the annular center under the action of a magnetic field and restraines upper shifting of central hightemperature region which causes by the stronger convection under the gravity condition. Under the magnetic conditions,velocity field is distributed in central symmetry,because some gravity is counteracted,and the action of Marangoni is revealed gradually. The velocity reduces obviously and the direction presentes a downward trend and points to the symmetry axis. Macrosegregation of solidification structure is improved effectively. Magnetic field restrains diffusion of L2 drops and Ostwald maturation,and also restraines the increase of L2drops＇ volume integral,thus contributes to the distribution of L2 drops.
出处
《金属热处理》
CAS
CSCD
北大核心
2017年第8期198-203,共6页
Heat Treatment of Metals
基金
国家自然科学基金(51401133)
辽宁省科学技术基金(20141074)
辽宁省教育厅科学研究项目(L2014230)
沈阳建筑大学博士后基金(SJZUBSH201620)
关键词
偏晶合金
凝固组织
磁场
数值模拟
monotectic alloy
solidification structure
magnetic field
numerical simulation
