Mg含量对金属型铸造Al-Mg合金的微观组织和枝晶形貌的影响  

Effects of Mg Content on Microstructure and Dendrite Morphology of Permanent Mold Casting Al-Mg Alloys

作　　者：郭海洋[1] 陈体军[1] 段天全[1] 孙明杰[1] 

机构地区：[1]兰州理工大学甘肃省有色金属新材料国家重点实验室,甘肃兰州730050

出　　处：《铸造》2013年第4期319-323,329,共6页Foundry

基　　金：国家自然科学基金资助项目(51061010)

摘　　要：利用OM、EM研究了Mg含量对金属型铸造Al-Mg合金微观组织和枝晶形貌的影响,并用EBSD(电子背散射衍射)研究了组织中柱状晶的生长取向。结果表明:不同成分的合金其组织主要由柱状晶区和等轴晶区组成,纯铝的柱状晶区最大,随着Mg含量的增加柱状晶区的宽度逐渐减小,当Mg含量达到15%时柱状晶区完全消失;一次枝晶间距则随Mg含量的增加而持续增加,且枝晶形貌由胞状晶转变为柱状树枝晶,最后变为等轴晶;Mg元素对Al-Mg合金中初生晶的生长取向有一定的影响,在Mg含量为2%时,枝晶生长取向以[100]晶向为主,同时还伴有[011]、[120]、[230]晶向,而Mg含量为10%时,枝晶的生长取向为[001]晶向。The microstructures and dendrite morphologies of permanent mold casting Al-Mg alloys with different Mg contents have been investigated by using OM, SEM. Simultaneously, the growth orientations of columnar crystals have been measured by using EBSD （electron backscattered diffraction） . The results show that the microstructures of all of the alloys are generally composed of two zones, columnar crystal zone and equiaxed grain zone. The width of the columnar grain zone is the largest for pure aluminum. The width decreases with the increase of the Mg content, and this zone completely disappears when the content is up to 15%. The primary dendrite arm spacing of the columnar dendrites continuously increases with the increase of the Mg content. The dendrite morphology changes from cellular crystal to columnar dendrite crystal, and finally turn into equiaxed one. Mg elements have certain effect on the crystal growth orientation in A1-Mg alloy： the main growth orientation for the alloy with 2% Mg is [100], and is accompanied by [011 ], [ 120], [230]; but when the Mg content increases to 10%, the growth orientation changes to [001 ].

关 键 词：AL-MG合金 枝晶形貌 一次枝晶间距 生长取向 

分 类 号：TG292[金属学及工艺—铸造]