以Al-Cu亚共晶合金为研究对象, 考察了 α-Al单晶磁各向异性对稳恒强磁场下定向凝固枝晶组织生长行为的影响. 实验测定了 α-Al单晶不同晶向的磁化率. 结果表明: Al-Cu单晶中的磁化现象表现出明显的方向性; 难磁化轴为晶体学位向<111>方向, 即磁化率最小; 易磁化轴为晶体学位向<311>或<310>方向, 即磁化率最大; 磁化率随Cu原子数量的增加而降低; [111]晶向族中4个晶向的磁化率不再一致. 对于Al-0.85%Cu合金, 当生长速度为50 μm/s时, 在无磁场情况下其定向凝固枝晶主干沿凝固方向排列; 当施加6 T纵向强磁场时, 枝晶主干偏离凝固方向成一定夹角排列, 这一现象可能是由 α-Al磁晶的各向异性所致.
This paper studies the effect of magnetic anisotropy of α-Al single crystal on the dendritic morphology in Al-Cu hypoeutectic alloy under a static high magnetic field during directional solidification. Magnetic susceptibility of α-Al single crystal slices with different crystal orientations are measured with the Faraday method. The results shows that the anisotropic and asymmetric magnetic property of the crystal cell of α-Al containing Cu. The <111>-crystal direction is a hard magnetization direction while <311> or <310>-crystal direction is an easy magnetization direction. Magnetic susceptibility decreases with increase of Cu content in α-Al. In addition, magnetic susceptibilities of the four crystal orientations among [111] are different. Besides, applying a 6 T longitudinal high magnetic field, the α-Al dendrite deviates from the heat flow direction, which is parallel to the solidification direction without a magnetic field at a growth speed of 50 μm/s.This phenomenon may be attributed to the crystal magnetic anisotropy energy of α-Al.
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