Numerical analysis of the hydrodynamic behaviour of immiscible metallic alloys in twin-screw rheomixing process

Abstract

A numerical analysis by a VOF method is presented for studying the hydrodynamic mechanisms of the rheomixing process by a twin-screw extruder (TSE). The simplified flow field is established based on a systematic analysis of flow features of immiscible alloys in TSE rheomixing process. The studies focus on the fundamental microstructure mechanisms of rheological behaviour in shear-induced turbulent flows. It is noted that the microstructure of immiscible alloys in the mixing process is strongly influenced by the interaction between droplets, which is controlled by shearing forces, viscosity ratio, turbulence, and shearing time. The numerical results show a good qualitative agreement with the experimental results, and are useful for further optimisation design of prototypical rheomixing processes.

Solidification of Al-Sn-Cu Based Immiscible Alloys under Intense Shearing

“…A detailed explanation of fluid flow in the MCAST unit is described elsewhere. [8,14,[19][20][21][22][23][24] Before beginning the experiments, the MCAST unit was heated to the semisolid region (processing temperature, T p ) of the alloy to be used. The melt was poured into the MCAST unit well above T c to avoid liquidphase separation before shearing commences.…”

Processing of Al-45Sn-10Cu Based Immiscible Alloy by a Rheomixing Process

“…3(b). The well dispersed slurry needs to be preserved by high cooling rate, otherwise the Sn-rich droplets start to aggregate very slowly by the Brownian motion [8]. In this investigation, the effect of the shearing temperature on the microstructure of the Al-45Sn-10Cu alloy was studied with fixed shearing time and speed with respect to the size and shape factor of the Sn-rich particles.…”