高剪切熔体处理下半固态A357合金浆料的组织特征研究  

Microstructural Features of Semi-Solid A357 Alloy Slurry Under High-Shear Melt Processing

作　　者：杨柳青[1] 徐骏[1] 刘国钧[1] FAN Z 

机构地区：[1]北京有色金属研究总院,北京100088 [2]布鲁内尔大学

出　　处：《铸造》2012年第2期143-146,共4页Foundry

基　　金：国际科技合作计划项目(2009DFB50210)

摘　　要：以A357铝合金为试验材料,利用双螺旋流变制浆设备进行了半固态浆料的制备工艺研究。考察了高剪切熔体处理,也即高强度的搅拌剪切和高强度的紊流作用下,搅拌速度和搅拌时间对铝合金非枝晶组织的形成以及组织特征的影响。结果表明:随着搅拌速度的提高,坯料组织中初生α-Al晶粒尺寸减小,形状变得圆整均匀,但是固相体积分数逐渐减小,搅拌速度的增大对球晶的生长起到了抑制作用;熔体在双螺旋设备中的凝固主要经历了连续冷却以及等温剪切两个过程,搅拌时间越长,晶粒越圆整均匀,尺寸越大,但晶粒密度会急剧下降,总的固相分数不会发生明显变化。The semi-solid slurry of A357 aluminum alloy was prepared by using of twin-screw rheomoulding device. Under high-shear melt processing, namely high intensity of turbulence and a cyclic variation of shear rate, the effects of rotation speed and shearing time on formation of non-dendritic microstructure of aluminum alloy were investigated. The experimental results show that the primary c^-Al particles become fine and nearly spherical with the increase of rotation speed, but solid volume fraction reduces gradually due to the inhibition of increasing rotation speed on the growth of globular particles; solidification of the melt inside the twin-screw rheomoulding device experiences two stages, the continuous cooling stage and the isothermal shearing stage. The primary α-Al particles grow and become spherical and uniform with the increase of shearing time, but density of α-Al particles reduces sharply, and solid volume fraction has no big change.

关 键 词：高剪切熔体处理 A357铝合金 半固态浆料 凝固组织 

分 类 号：TG111[金属学及工艺—物理冶金]