7050铝合金均匀化热处理后的组织转变  

Microstructure Evolution in DC (Direct Casting) 7050 Alloy during Homogenization

作　　者：曹志强[1] 刘吉东[1] 张红亮[1] 李廷举[1] 王家淳[2] 

机构地区：[1]大连理工大学铸造工程研究中心 [2]苏州有色金属研究院有限公司

出　　处：《特种铸造及有色合金》2010年第4期297-299,共3页Special Casting & Nonferrous Alloys

基　　金：国家自然科学基金资助项目(50274018)

摘　　要：利用金相组织观察、差示扫描量热法、扫描电镜、X射线衍射等手段对7050铝合金铸态组织、不同条件下的均匀化效果和均匀化前后的组织转变进行了分析。结果表明,7050合金半连续铸锭中存在大量具有η-MgZn2型晶体结构的非平衡第二相Mg(AlZnCu)2,其熔化温度为477℃,在均匀化处理过程中,该非平衡凝固共晶相在477℃向合金基体溶解并转变成Al2CuMg(S相),S相在该合金中的熔化温度为490℃;在460℃均匀化处理时,结晶相η全部消失,晶间和晶内均出现球状S相。在随后的冷却过程中η相和S相先后在晶内析出,但在260℃时S相再一次消失。The as-cast and homogenized microstructure of DC 7050 aluminum alloy were investigated by differential scanning calorimeter (DSC), optical microscope (OM),scanning electron microscope (SEM) and X-ray diffraction (XRD). The results reveal that there exists an amount of non-equilibrium Mg(AlZnCu)2 phase with η-MgZn2 crystal structure in DC 7050 aluminum alloy ingots. The non-equilibrium phase is fully dissolved into the alloy matrix at 477℃ to further transform into large spherical Al2CuMg (S phase) at 490℃. With homogenization treatment at 460℃, the non-equilibrium Mg(AlZnCu)2 phase with η-MgZn2 crystal structure totally disappeares in the alloy with occurrence of spherical S phase in both intercrystal and grain. During cooling process, η-MgZn2 phase and S phase are precipitated from the grain subsequently, however, S phase disappears in the grain of the 7050 alloy ingots at 260℃.

关 键 词：7050铝合金 DC连铸 均匀化处理 结晶相 

分 类 号：TG166.3[金属学及工艺—热处理] TG151.1[金属学及工艺—金属学]