This can be used to fill the cavity at a lower speed and with laminar flow. This enables a better filling of the cavity, lower porosity and improved mechanical properties.
But why does the slurry keep its temperature? This has to do with latent heat. Latent heat is the energy released or absorbed by a body or a thermodynamic system during a constant-temperature process, usually a first-order phase transition. So if the liquid aluminium solidifies, the energy difference between the liquid and the solid state is spread into the surrounding area. For melting, energy is taken from the surrounding area.
The effect is shown in the video in this article. The temperature stays level for half an hour. As soon as most of the ice melts, the temperature increases rapidly. The Rheocasting slurry works on the same principle.
A slurry is made of a mixture of liquid metal and already-globular solidified metal. But be aware that not all Rheocasting methods will enable to generate a homogeneous and consistent slurry. Therefore, the Comptech AB Rheometal Process is recommended because it is the only one that is not temperature regulated.
Back to the slurry. The globular solid particles are a point of solidification for the liquid melt. The latent heat of the solidification heats up the surrounding metal. Therefore, enabling it to flow even further.
That's why we love Rheocasting!
