In semisolid aluminium alloys, flow of liquid metal
through the evolving interdendritic channels is driven by
an approximate 7% volumetric shrinkage [15] associated
with the liquid-to-solid phase transformation. The permeability
of such alloys has traditionally been measured using
an apparatus that applies a pressure gradient to a partially
solid sample while measuring the discharge velocity of a
working fluid. Studies using this type of device (e.g.
[16–23]) have focused on measuring the near-eutectic permeability
of equiaxed dendritic structures while attempting
to reduce errors associated with the tendency of the microstructure
to change during testing due to coarsening and
other diffusion processes