Microstructure of Al–Mg–Si–La alloy under pulsed magnetic field treatment during solidification

Abstract

The grains refinement and secondary phase modification mechanism of Al–Mg–Si–La alloy under pulsed magnetic field during solidification were studied in detail. With application of pulsed magnetic field, the microstructure of Al–Mg–Si–La alloy consists of fine and equiaxed grains. Meanwhile, the smaller size of Mg2Si homogeneously dispersed in α-Al grains, and the number of AlFeSi and LaAlSi phase obviously decreased compared with the ones without pulsed magnetic field treatment. The cluster nucleation at the liquid region during early solidification stage is dominant reason for grains refinement in Al–Mg–Si–La alloy under pulsed magnetic field. Theoretical calculation indicated that pulsed magnetic field provides maximum energy in the alloy melt at about 760°C, which decreased the critical radius and energy barrier for nucleation.