MICROSTRUCTURES AND DISTRIBUTION OF ALLOYING ELEMENTS OF LY12 Al-ALLOY MODIFIED BY A PULSED CURRENT

The effect of pulsed current on the microstructures and distribution of alloying elements of LY12 Al alloy during solidification process was studied. The experimental result showed that the microstructures of a LY12 Al alloy was evidently changed by pulsed current treatment, the eutectic structure which aggregated at grain boundary and dendrite net, was greatly reduced. The net became discontinuous, the dispersive and approximately spherical eutectic particles were formed inside the grains and near the boundary. The pulsed current can effectively reduce the segregation of Cu and Mg in the alloy, especially for Cu, and can remarkably improve the negative segregation phenomena of Cu in Al alloy, make Cu element more uniformly distributed in the whole sample.