New Development of Electromagnetic Processing of Materials

1)利用超导磁体，研究了强磁场（5T）对析出相排列和晶向控制的影响。由Mn-4wt%Bi合金析出的金属间化合物BiMn与施加磁场方向平行排列，由Al-11wt%Si-2wt%Fe合金析出的金属间化合物AlSiFe与施加磁场方向垂直排列。水中的碳纤维取向与磁场方向平行。实验中发现了a面和b面垂直于磁场的事实。这些证据在理论上得到了证实。2)为了明确强磁场对合金浓度分布的影响，采用垂直Bridgeman法在强磁场下对（Bi_<0.25>Sb_<0.75>） Te_3进行了欠定向凝固。Bi在中心部分的浓度沿生长方向和径向分布较高，Bi_2Te_2在中心部分偏析。这个原因是从理论的角度来考虑的。3)利用数学模型研究了磁场对立方容器内导电流体自然对流的影响。在不可压缩流体假设和Boussineq近似的条件下，求解了由质量、能量和动量平衡组成的模型。从模型中可以看出，在一定范围内，随着磁场强度的增大，传热得到增强。4)在磁场作用下，利用抗磁性硅油液滴在稀释的磁性流体中悬浮，证明了液滴在磁化力作用下的悬浮和稳定，并建立了数学模型。得到了以下结果：在不溶性磁性流体和非磁性流体共存的条件下，只需施加弱磁场即可使抗磁性液滴悬浮。磁化率比周围介质小的抗磁性液滴，在朝向中心部位的磁化力作用下，面对相同极性所产生的磁场，稳定在两极之间的中心部位。少

1) By use of a super conductingmagnet, the effects of a strong magnetic field (5T) on the alignment of precipitating phase and the control of crystal orientation were studied. The intermetallic compound BiMn precipitating from Mn-4wt%Bi alloy aligns in parallel to the imposed magnetic field direction and the intermetallic compound AlSiFe precipitating from Al-11wt%Si-2wt%Fe aligns in perpendicular to the magnetic field direction. The carbon fibers in a water are oriented in parallel to the magnetic field direction. The fact that a-and b-planes align in perpendicular to the magnectic field was found in the experiment. These evidences were confirmed in the theoretical consideration.2) In order to clarify the effect of a strong magnetic field on the concentration profiel of an alloy, the uniderectional solidification of (Bi_<0.25>Sb_<0.75>) Te_3 was carried out using the vertical Bridgeman method under a strong magnetic field. The concentration of Bi in the center part is increasing along … More the grouth direction and the radial distribution of Bi is high at the center part and Bi_2Te_2 segregates there. This reason was considered from the theoretical view point.3) The effect of a magnetic field on the natural convection of an electrically conductive fluid in a cubic vessel was studied by use of a mathematical model. The model which consists of the mass, energy and momentum balances was solved all together under the assumptions of incompressible fluid and the Boussineq's approximation. From the model it is found that the heat transfer is enhanced with increase of the intensity of the magnetic field in some ranges.4) The levitation of a droplet and its stabilization due to the magnetization force was demonstrated by using a diamagnetic slicon oil droplet in a diluted magnetic fluid under a magnetic field and a mathematical model was developed. The following results were obtained.1.The diamagnetic droplet can be levitated under the coexistence of unsoluble magnetic and nonmagnetic fluids by only imposition of a weak magnetic field.2.The diamagnetic droplet which has smaller magnetic susceptibility than the surrounding medium was stabilized in the center part between poles under the magnetic field created by facing the same polarity dur to the magnetization force directing toward the center part. Less