基于小润湿角下脉冲磁场的凝固形核模型

Solidification Nucleation Model Based on Small Wetting Angle Under Pulsed Magnetic Field

基于Ma形核模型,理论分析了异质形核基底小润湿角下脉冲磁场金属凝固的异质形核过程,建立了凝固形核模型.考察脉冲磁场磁感应强度对金属凝固临界形核半径及临界形核过冷度的影响.结果表明:该模型中体系Gibbs自由能与异质形核基底形状系数无关.在低过冷度金属凝固条件下,当脉冲磁场磁压力功与金属熔体固液自由能差在同一数量级时,脉冲磁场可有效减小凝固形核的临界半径;在大过冷度(大于20℃)金属凝固条件下,脉冲磁场对金属凝固临界形核半径的影响可忽略.金属凝固异质形核基底粒径较大时,临界形核过冷度随脉冲磁场磁感应强度增大而有效减小.

Heterogeneous nucleation of small wetting angle under pulsed magnetic field（ PMF） was theoretically analyzed on the basis of the Ma nucleation model,with the solidification uncleation model established. The effects of magnetic induction intensity of PMF on the critical nucleation radius and critical undercooling were investigated. The results showed that Gibbs free energy of the model has nothing to do with shape coefficient of heterogeneous nucleation substrate. When the work done by magnetic pressure is the same order as solid-liquid free energy difference under low undercooling,the PMF can effectively reduce the critical uncleation radius,and the effect of the PMF on the critical uncleation radius can be ignored under high undercooling（ 20 ℃）. When the substrate size is larger,the undercooling of critical uncleation decreases with increasing magnetic induction intensity of the PMF.