Temperature-Dependent Constitutive Behavior and Fractionation of Semi-Solid Slurries

9612497 Ilegbusi半固态材料的加工已成为生产接近净形状零件的一种潜在的有吸引力的方法。通常通过控制易偏析合金的显微组织来实现。然而，人们对半固态材料的流变学和流动特性还缺乏认识。浆料在模具延伸处和窄截面处经常出现分馏现象。这种现象导致本构响应的不均匀性，从而在固化产品中产生不可接受的差异凝固和不均匀的机械性能。该研究项目通过开发模型来研究半固态浆料的非等温本构关系来解决这些问题。将研究两种测试材料：锡铅合金和铝铜合金。这些材料将在没有和存在外部施加的碳化硅和氧化铝颗粒的情况下进行研究。将进行平行实验，研究一系列操作条件下的充型特性。本课题具有理论与实验相结合的特点，对制造业中的近净形状工程具有实际意义。

9612497 Ilegbusi Processing of materials in the semi-solid state has become a potentially attractive means of producing near net-shape parts. It is often achieved by controlling the microstructure from segregation prone alloys. However, there still exists a lack of understanding of the rheology and flow characteristics of the semi-solid state. The slurries often exhibit fractionation at mold extension and narrow sections. This phenomenon contributes to inhomogeneity of constitutive response and consequently produces unacceptable differential solidification and non-uniform mechanical properties in the solidified product. The research project addresses these issues by developing models to study the non-isothermal constitutive relationship for semi-solid slurries. Two test materials will be investigated: a tin-lead alloy and an aluminum-copper alloy. These materials will be studied both in the absence and presence of externally-imposed particulates of silicon carbide and aluminum oxide. A parallel experiment will be carried out to study the mold-filling characteristics under a range of operating conditions. This project has a balance between theory and experiment and could have a practical impact to the near-net shape engineering in manufacturing.