This study investigates the microstructural stability and consequent rheological behavior of Al-Si-Cu in the semi-solid state. It covers different stages in the production of the alloy, characterization of the microstructure in the as-cast condition and the effect of reheating to a semi-solid slurry on the microstructure and viscous behavior. Al3Si2.5Cu, Al5Si2.5Cu, and Al7Si2.5Cu alloys were produced by conventional casting with intense electromagnetic stirring. The alloys were then reheated to temperatures corresponding to 45 and 60 pct, solid fractions and held at these temperatures for 0, 30, 90 and 210 second to investigate spheroidization of the solid phase immersed in liquid. The best rheological behavior was achieved for alloys reheated to a 45 pct solid fraction, which had an apparent viscosity of around 1 Pa s, like glycerol, or even 10 Pa s, like honey, for strains of up to 65 pct. However, for strains of between 65 and 80 pct the viscosity increased rapidly to 10⁴ to 10⁵ Pa s. These values are similar to those for molten glass and are a result of the start of solid–solid interaction. Even with viscosities as high as these, all the alloys exhibited excellent formability in the semi-solid state regardless of their silicon content.

本研究研究了半固态 Al-Si-Cu 的微观结构稳定性和随之而来的流变行为。它涵盖了合金生产的不同阶段、铸态微观结构的表征以及再加热至半固态浆料对微观结构和粘性行为的影响。Al3Si2.5Cu、Al5Si2.5Cu 和 Al7Si2.5Cu 合金是通过常规铸造在强烈的电磁搅拌下生产的。然后将合金重新加热到对应于 45 和 60% 固体分数的温度，并在这些温度下保持 0、30、90 和 210 秒，以研究浸入液体中的固相的球化。合金再加热到 45% 的固相分数，其表观粘度约为 1 Pa s，如甘油、或什至 10 Pa s，像蜂蜜一样，为高达 65 pct 的菌株。然而，对于 65 和 80 pct 之间的菌株，粘度迅速增加到 10⁴到 10 ⁵  Pa s。这些值类似于熔融玻璃的值，是固-固相互作用开始的结果。即使具有如此高的粘度，所有合金在半固态下都表现出优异的成型性，而与它们的硅含量无关。