Fabrication of thin silicon flakes through dealloying from laser directed energy deposition Ca-Si alloys

Abstract

In this study, thin silicon flakes were fabricated through dealloying from laser directed energy deposition (LDED) Ca-Si alloys, and the solidification mechanism of the lamellar eutectic microstructure was studied. With 1200 W laser power and 450 mm/min scanning speed, the LDED Ca-Si alloys have a fine lamellar eutectic microstructure and are easily separated from copper substrates. After dealloying in the diluted HCl solution for 6 h, the thin silicon flakes ranging in thickness from 100 nm to 0.5 μm were obtained. The formation of the thin flakes was attributed to fine lamellar Si phases in precursor alloys. The rapid solidification of laser processing could refine the microstructure, especially Si phases, and improve the chemical homogeneity of the material. Combining laser processing and dealloying, a cost-effective and scalable strategy was devised to fabricate fine powder from a laser processing optimized microstructure.