3-D morphology and growth mechanism of primary Al₆Mn intermetallic compound in directionally solidified Al-3at. % Mn alloy

详细信息    查看全文

• 作者：Huijun Kang ; Xinzhong Li ; ^{hitlxz@126.com} ; Yanqing Su ; Dongmei Liu ; Jingjie Guo ; Hengzhi Fu
• 关键词：A. Intermetallics ; miscellaneous ; C. Crystal growth ; D. Microstructure
• 刊名：Intermetallics
• 出版年：2012
• 出版时间：April 2012
• 年：2012
• 卷：23
• 期：Complete
• 页码：32-38
• 全文大小：1218 K

文摘

3-D morphology and growth mechanism of primary Al₆Mn intermetallic compound have been investigated in directionally solidified Al-3at. % Mn alloy at a low growth rate of 1?¦Ìm/s. A faceted growth of primary Al₆Mn with strong anisotropy has been observed. Its 3-D morphology exhibits elongated, hollow and distorted polyhedron with concave surfaces. This mainly depends on the crystal structure and growth conditions. Al₆Mn crystals tend to form regular octahedron bounded by eight {110} planes according to the crystal structure. The nonuniform transport of heat and solute during directional solidification increases the disparity in growth rates of crystal planes and strengthens the growth anisotropy. The growth of primary Al₆Mn is controlled by a screw-dislocation mechanism and terminates when nucleation of a new crystal occurs which is preferential on the concave surface. The discontinuous growth and nucleation of Al₆Mn crystal lead to a final stacking structure.