流变成形浆料制备技术发展动向及其对策

Developing Tendency and Countermeasures of Rheoforming Slurry-making

出了流变成形对半固态浆料的质量要求 ,归纳了与流变成形相应的半固态浆料制备新工艺。指出半固态金属流变成形的关键技术为如何快速获得理想的等轴非枝晶半固态组织 ,固相率、晶粒形状、晶粒尺寸和粘合度是表征半固态浆料的主要指标。介绍了低转速输送管控制浇注制备半固态浆料的新工艺 ,半固态组织的主要指标可达到 :①形状因子 1.0 8～ 1.3 6;②固相率 2 0 %～ 60 % ;③晶粒平均直径 40～ 10 0 μm ;④固相体积粘合度小于 0 .2 2。介绍了等轴非枝晶形成机理的研究现状 ,指出微观组织数值模拟技术是研究等轴非枝晶形成机理的新趋势、新思路 ,采用元胞自动机模拟技术对其进行了初步研究。

One of key aspects of semi-solid rheoforming is to quickly produce semi-solid slurry related to the microstructure obtained by remelting process in thixoforming.The contribution to requirements for semisolid slurry and some new slurry-making processesing in criteria are presented to describe a certain microstructure suitable for rheoforming.A controlling pouring process with a low rotating duct was presented to efficiently produce top-quality semisolid slurry.The four criteria of slurry produced by the new rheoforming process were:solid fraction 20%～60%,shape factor 1.08～1.36,average grain diameter 40～100 μm and volume contiguity less than 0.22.Finally,formation mechanism of equiaxed non-dendrite were reviewed and some primary investigation results were presented.