Microstructure and crystal growth direction of Al-Mg alloy  

作　　者：Ti-jun Chen Hai-yang Guo Xiang-wei Li Yuan Hao 

机构地区：[1]Key Laboratory of Gansu Advanced Nonferrous Metal Materials, Lanzhou University of Technology

出　　处：《China Foundry》2015年第2期129-135,共7页中国铸造（英文版）

基　　金：financially supported by the National Natural Science Foundation of China(Grant No.51061010);the Program for New Century Excellent Talents in University of China(Grant No.NCET-10-0023);the Program for Hongliu Outstanding Talents of Lanzhou University of Technology

摘　　要：The microstructures and crystal growth directions of permanent mould casting and directionally solidified Al-Mg al oys with different Mg contents have been investigated. The results indicate that the effect of Mg content on microstructure is basical y same for the al oys prepared by these two methods. The primary grains change from cel ular crystals to developed columnar dendrites, and then to equiaxed dendrites as the Mg content is increased. Simultaneously, both the cel ular or columnar grain region and the primary trunk spacing decrease. Al of these changes are mainly attributed to the constitutional supercooling resulting from Mg element. Comparatively, the cellular or columnar crystals of the directionally solidified alloys are straighter and more paral el than those of the permanent mould casting al oys. These have straight or wavy grain boundaries, one of the most important microstructure characteristics of feathery grains. However, the transverse microstructure and growth direction reveal that they do not belong to feathery grains. The Mg seemingly can affect the crystal growth direction, but does not result in the formation of feathery grains under the conditions employed in the study.The microstructures and crystal growth directions of permanent mould casting and directionally solidified Al-Mg alloys with different Mg contents have been investigated. The results indicate that the effect of Mg content on microstructure is basically same for the alloys prepared by these two methods. The primary grains change from cellular crystals to developed columnar dendrites, and then to equiaxed dendrites as the Mg content is increased. Simultaneously, both the cellular or columnar grain region and the primary trunk spacing decrease. All of these changes are mainly attributed to the constitutional supercooling resulting from Mg element. Comparatively, the cellular or columnar crystals of the directionally solidified alloys are straighter and more parallel than those of the permanent mould casting alloys. These have straight or wavy grain boundaries, one of the most important microstructure characteristics of feathery grains. However, the transverse microstructure and growth direction reveal that they do not belong to feathery grains. The Mg seemingly can affect the crystal growth direction, but does not result in the formation of feathery grains under the conditions employed in the study.

关 键 词：Al-Mg alloy MICROSTRUCTURE crystal growth direction feathery grains permanent mould casting directional solidifi cation 

分 类 号：TG146.21[一般工业技术—材料科学与工程]