高纯铝旋转偏析行为研究

采用自主研制的高纯铝的旋转偏析设备、 Element GD型辉光放电质谱仪（GDMS），结合界面稳定性理论，研究了偏析速度和旋转速度对高纯铝提纯效果的影响以及杂质元素在偏析锭上的分布特征。结果显示：晶体以平界面生长的临界速度为52 mm/h。偏析速度增加，导致杂质元素在晶体中的浓度明显增加，提纯率显著降低，偏析速度增加破坏原有稳定扩散状态，改变了杂质元素分凝能力。旋转速度增加，诱发杂质元素在晶体中的浓度明显降低，提纯率显著增加，旋转偏析有效提高熔体温度梯度，降低有效分配系数（Ke），改善晶体提纯效果。平衡分配系数（K0）<1的杂质元素含量从偏析锭心部到表面逐渐增加，K0>1的杂质元素正好相反，杂质元素浓度极差表明偏析锭底部均匀性最好。

Rotary Segregation Behavior of High Purity Aluminum

The effects of segregation velocity and rotation velocity on the purification of high purity aluminum and the distribution characteristics of impurity elements on the segregation ingot were studied by using a self-developed rotary segregation equipment for high purity aluminum and an element glow-discharge mass spectrometer (GDMS) combined with the interface stability theory. The results showed that the critical growth rate of crystal with flat interface was less than 52 mm/h. With the increase of segregation rate, the concentration of impurity elements in the crystal increased significantly, and the purification rate decreased significantly. With the increase of segregation rate, the original stable diffusion state was destroyed, and the separation ability of impurity elements was changed. With the increase of rotation speed, the concentration of impurity elements in the crystal was significantly reduced, and the purification rate was significantly increased. The rotation segregation could effectively improve the melt temperature gradient, reduce the effective partition coefficient (Ke), and improve the crystal purification effect. Impurity contents of K0<1 gradually increased from the center to the surface of the ingot, but impurity contents of K0>1 were just the opposite. The concentration range of impurity elements showed the best uniformity at the bottom of the ingot.