【摘要】 研究了双螺杆结构对AZ91D半固态镁合金浆料组织的影响,并与单螺杆的制浆效果进行了比较。试验结果表明,2种高剪切速率的双螺杆制浆机均可获得固相率为15%~60%、晶粒平均直径为35~55μm的超细球团状组织。由于组合式双螺杆由输送、剪切、混合等结构元件组成,加强了剪切与混合元件捏合处熔体的均匀化和剪切效果,使得双螺杆组合式结构比单一螺距结构的混合效果更好,得到的半固态镁合金组织更细小、更圆整。单螺杆制浆机由于其剪切速率低,对物料的混合作用不强烈,制备的非枝晶组织呈条状或不规则块状分布,晶粒平均直径为60~80μm。更多还原

【Abstract】 Effects of twin-screw structure on the microstructure of semi-solid Mg alloy slurry have been investigated, meanwhile, comparison between effects of twin-screw and of single-screw has been conducted. Experimental results indicate that fine spheroidized structure with average diameter of 40~60 μm in the slurry can be prepared by both combination twin-screw stirring and single screw thread twin-screw with high shearing rate, where the range of solid fraction can be controlled from 15% to 60%. However, compared with single screw thread twin-screw structure, the combined twin-screw structure can take more stirring effects due to the delivery, shearing, mixing mechanism, strengthening homogenization of the melt and shearing effects, thus the structure of semi-solid magnesium with finer and more round can be obtained. In contrast, because of the weak effects of mixture with low shearing rate, the solidified microstructure of the slurry prepared by single screw is strip shape or anomalous block with the primary grain size in the range of 60~80 μm.更多还原