Microstructure and phase evolution during the dealloying of bi-phase Al–Ag alloy

The chemical dealloying of bi-phase Al-35Ag alloy has been investigated within the parting limit. The dealloying of α-Al(Ag) and Ag2Al commenced simultaneously, and all α-Al(Ag) and part of Ag2Al were dealloyed, leaving residual Ag2Al to be dealloyed afterwards. The dealloying of the residual Ag2Al is associated with vacancy controlled mechanism and diffusion of Al atoms. It is revealed that the diffusions of the Al and Ag atoms during dealloying are significant. The Ag skeletons formed at the initial stage, and became coarsened gradually with a time dependence of d ∝ t2/5, illustrating the vital role of diffusion of Ag atoms.

► Selective leaching of α-Al(Ag) and Ag2Al occurs simultaneously during dealloying.
► Diffusion of Al and vacancy controlled mechanism dominate the etching of Ag2Al.
► The coarsening of ligaments in NPS follows a time dependence of d ∝ t2/5.