Formation mechanism of gradient structure of aluminum matrix composite under static magnetic field during directional solidification

Aluminum matrix composite, as a new electronic packaging material, has attracted the attention of researchers. Effect of magnetic field on gradient structure of aluminum matrix composites (Al-21wt.%Si and Al-40wt.%Cu) has been investigated during directional solidification. Experimental results show that the application of static magnetic field results in the formation of gradient structure during directional solidification. Numerical simulation results and a proposed theoretical model indicate that gravity, temperature field and thermoelectric (TE) magnetic convection are beneficial to the precipitation and growth of the primary phases. Finally, the primary phases precipitate and grow rapidly near the initial solidification interface, leading to the gradient structure. This work facilitates the understanding of forced flow greatly changing the solidification structure of aluminum matrix composite under magnetic field during directional solidification.