Microstructural modification of in-situ aluminum matrix composites via pulsed electromagnetic processing of crystallizing melt

Cast hypereutectic Al - Mg2Si in-situ aluminum matrix composites are promising for industrial application as lightweight structural materials with high resistance under conditions of dry and abrasive wear, elevated temperatures and loads. In this work, the effect of melt irradiation by nanosecond electromagnetic pulses during crystallization on the structure formation of Al + 25 wt.% Mg2Si composites was studied. The application of nanosecond electromagnetic pulses to the crystallizing composite melt at the tested frequency parameters (0.5 and 1 kHz) and pulse amplitude (21.7, 31.5, 36.5, 42 kV) allows to decrease the average size of primary Mg2Si particles to values in the range from 40 to 65 & mu;m. It was shown that during irradiation of crystallizing composite melt with frequency 1 kHz and amplitude 21.7 kV the most finely dispersed eutectics of completely rod-like morphology is revealed in the structure of the samples. At these parameters of pulsed electromagnetic processing, a decrease in the average size of Mg2Si particles to 44.12 & mu;m was achieved, while in untreated composites their size averaged 147.69 & mu;m. The observed number of Mg2Si particles in the section field increases by more than an order of magnitude compared to the initial state. The obtained data show a high potential of practical use of the tested technical solutions for the modifying treatment of hypereutectic composites of the Al - Mg2Si system.