The semi-solid ZL201A alloy slurry was prepared by the low superheating pouring at 678

663

648℃ and weak electromagnetic stirring method

and microstructure of the samples was observed by optical microscope.The results reveal that with decreasing in pouring temperature

primary α-Al grains in the semi-solid ZL201A aluminum alloy slurry are changed from rosette to spherical shape with refinement of grain size and more homogeneous distribution

meanwhile

that in the edge and bottom of the slurry are converted from coarse dendrite into rosettes.The appropriate temperature for preparation of semi-solid ZL201A aluminum alloy slurry is 663℃ under the given conditions.The refinement of primary α-Al grains is attributed to the weak electromagnetic stirring homogenizing the temperature field of liquid ZL201A alloy and widening the region of simultaneous solidification

meanwhile

the latent heat of the ZL201A aluminum alloy is released during a shorter period

which promotes the secondary arm roots of the rosette α-Al grains to be melted

accelerating the formation of spherical α-Al grains.