Concurrence of de-alloying and re-alloying in a ternary Al67Cu18Sn15 alloy and the fabrication of 3D nanoporous Cu–Sn composite structures

Abstract

We report the concurrence of de-alloying and re-alloying in a ternary Al₆₇Cu₁₈Sn₁₅ alloy (at.%) de-alloyed in a 5 wt% hydrochloric acid (HCl) solution at 70 ± 2 °C, and the fabrication of three-dimensional (3D) nanoporous Cu₃Sn–Cu–Cu₆Sn₅ composites in the form of self-supporting foils. Re-alloying occurred in Al₆₇Cu₁₈Sn₁₅ compared to de-alloying alone in binary Al–Cu alloys. Both Cu₃Sn and Cu₆Sn₅ phases formed through an accompanied re-alloying process. This finding further proves the temperature sensitivity of phase formation in the Cu–Sn system established from Cu–Sn diffusion couple studies, and demonstrates the capability of designing and creating nanoporous composite materials via de-alloying a multicomponent alloy.