Influence of Parameters of Melt Processing by Nanosecond Electromagnetic Pulses on the Structure Formation of Cast Aluminum Matrix Composites

Abstract

The work is aimed at establishing the effect of nanosecond electromagnetic pulses (NEPs) with different amplitudes on the formation of the structure of cast aluminum matrix composites of the pseudo-binary Al–Mg₂Si system with hypoeutectic (5 wt % Mg₂Si) and hypereutectic (15 wt % Mg₂Si) composition. With an increase in the amplitude of the generator of NEPs in alloys with 5 and 15 wt % Mg₂Si, the structural components of the matrix alloy (α-solid solution and eutectic) are refined, while no significant differences in the sizes and morphology of primary crystals of Mg₂Si in the hypereutectic range of compositions were observed in the entire range of tested variants of the amplitude of the generator of NEPs. Presumably, the observed nature of the influence of NEPs on the structure of composites in the hypereutectic region of compositions is associated with the features of their crystallization behavior. The temperature range of the existence of the two-phase region L + Mg₂Si is much lower than the temperatures of irradiation with NEPs; apparently, in connection with this, NEPs do not affect the thermodynamic state of the interfaces “primary crystal Mg₂Si–melt.” It has been shown that a promising option for the simultaneous modifying effect on all structural components of Al–Mg₂Si aluminum matrix composites (solid solution, eutectic, primary Mg₂Si particles) is a combination of thermal-rate treatment and irradiation of melts with NEPs, as well as additional processing of melts by NEPs during solidification.