Effect of electromagnetic stirring way and rare earth on solidification structure of semi-solid A356 alloy

The slurry of semi-solid A356 aluminum alloy was prepared by the mode of two-way electromagnetic stirring, combined with rare earth elements. The effects on its morphology of primary phase were investigated in the way that no rare earth, single rare earth 0.5 %Ce(mass fraction, similarly hereinafter) and mixed rare earth 0.3 %La+0.2 % Yb were applied to be stirred for 12 s in electromagnetic stirring modes (one-way continuous stirring, two-way continuous stirring, and two-way intermittent stirring) in the magnetic field with a frequency of 30 Hz by the ways of OM, XRD and SEM. The results indicate that when the total percentagecontent of RE is the same, mixed RE is better than the other two in optimizing the solidification microstructure of the alloy with the average of the equal-area-circle diameter and shape factor of the primary phase reaching 36.4 um and 0.82.On the basis of this, the melt was treated with different mixing methods. This experiment shows that the strong turbulence and inertial impact are formed by two-way continuous stirring, andthen accelerate the mass and heat transfer in the solidifying system, in which the size and morphology of grainsaremore finer and round compared to one-way continuous stirring and two-way intermittent stirring.