Selective matrix dissolution in an Al–Si eutectic

The irregular structure of an Al–Si eutectic has been chemically modified by adding small amount of Sr (300 ppm). The initially coarse flake structure was converted into technologically preferable fine fibrous morphology. The selective phase dissolution has been investigated using two different electrochemical approaches, derived from superimposed Pourbaix diagrams. Anodisation at 0.3 V (SHE) in 1 M HCl led to pitting and was partially successful after an extended period of time (20 h). Electropolishing in a mixture of perchloric acid and methanol (10:90) at 0 °C proved successful in both the partial and the complete matrix dissolution, without affecting silicon structures.