Spheroidization Behavior of Nano-Primary Silicon Induced by Neodymium under High-Current Pulsed Electron Beam Irradiation

Abstract

The spheroidization behavior of the nano-primary silicon phase induced by Nd under high-current pulsed electron beam (HCPEB) irradiation was investigated in this study. The study results revealed that, compared to the Al–17.5Si alloy, spheroidized nano-primary silicon phase emerged in the alloy’s HCPEB-irradiated surface layer due to the presence of Nd. Because Nd was abundantly enriched on the fast-growing silicon crystal plane, its surface tension was reduced under the extreme undercooling caused by HCPEB irradiation, causing the growth velocity of each crystal plane to be the same and spherical nanometers of silicon to appear. The spheroidization of nano-primary silicon phases occurred in the remelted layer. The microhardness test revealed that Nd could depress the microhardness of the Al matrix at the same number of pulses, but conversely increase the microhardness of the primary silicon phase, compared to the Al–17.5Si alloy. The tribological test showed that the presence of spherical nano-primary silicon could significantly improve the alloy’s tribological property.