【摘要】 研究了 Bi- Mn合金从固液两相区开始凝固 ,合金中 Mn Bi相在磁场中形成定向排列组织的临界条件及其变化规律。实验研究表明 ,Bi- Mn合金中 Mn Bi相在磁场中的定向排列能够迅速形成 ;Mn Bi相形成定向排列组织所需的临界温度随外磁场强度的增大而降低 ;恒温温度相同时 ,6 % Mn合金形成定向排列组织所需的临界磁场强度高于 3%Mn合金。在临界值以上 ,定向排列因子Γ随恒温温度的升高和磁场磁感应强度的增强而增大。理论分析结合实验研究表明 ,合金中 Mn Bi晶体在磁场中取向的机制主要是旋转取向 ,晶体取向驱动力主要是晶体具有磁各向异性 ,在磁场中磁化过程中所受的磁力矩 ,阻力主要是晶体间碰撞阻碍更多还原

【Abstract】 The critical conditions needed to form MnBi regular structure have been studied experimentally in this paper during the solidification started from mushy zone of Bi Mn alloys with a magnetic field It is found that the formation of MnBi regular structure in Bi Mn alloy could be achieved rapidly in a magnetic field The critical holding temperature in 6%Mn alloy is increased with the decrease of the applied magnetic field The critical magnetic intensity need to form MnBi alignment structure in 6%Mn alloy was higher than that in 3%Mn alloy at the same holding temperature And beyond the critical conditions the alignment degree Γ of MnBi phase was increased with the increase of the holding temperature and the magnetic flux densty The theoretic analyses combined with the experimental results show that the MnBi crystals in Bi Mn alloy rotate to align along the magnetic field The orientation of the crystal is promoted mainly by the magnetic moment due to the magnetic anisotropic crystal magnetizes in the field and impedes mainly by the impact between the crystals during their rotation更多还原