【摘要】 提出了合金凝固过程中晶粒磁取向的动力学模型,获得了晶粒取向时间的分析解,确定了取向时间与介质粘度、晶粒长径比、晶粒各向异性磁化率差以及磁场强度的理论关系.应用这个关系对顺磁性超导材料Bi-2212和磁性材料Bi-3％Mn的取向时间进行了预测.将Bi-3％Mn合金在300℃下熔化,并在不同的磁场下淬火,获得了有取向的MnBi织构,晶粒的取向时间小于1s,与理论预测一致.更多还原

【Abstract】 A model responsible for the magnetic--induced rotation of single anisotropic grainin free medium has been proposed firstly based on the classical dynamics of rigid body, in whichthe grain is treated as a prolate spheroid. A theoretical expression was derived for the alignmenttime of grain as a function of viscidity of liquid matrix, aspect ratio of grain, difference of anisotropicmagnetic susceptibility of grain and applied magnetic intensity It was applied to predict the alignmenttime of paramagnetic superconductor material Bi--2212 and ferromagnetic material Bi--3%Mn in meltprocessing. An experiment was conducted for the latter melted fully at 300℃ then rapidly quenchedunder different applied magnetic field, and the MnBi texture is obtained. It is found that the alignmenttime is less than one second, in good agreement with the theoretical prediction.更多还原