Al-Pd alloy formation by aluminium underpotential deposition onto palladium from chloroaluminate melt

Abstract

Aluminium was underpotentially deposited onto palladium substrate from the equimolar AlCl3+NaCl melt at 250º and 300 ºC. Electrochemical methods used were linear sweep voltammetry and potential step. The obtained samples were analysed by scanning electron microscopy, energy dispersive spectroscopy, atomic force microscopy and X-ray diffraction. The aluminium underpotential deposition is followed by interdiffusion of very thin Al deposit and Pd substrate which lead to the formation of surface Al-Pd intermetallic compounds. The constant-potential regions measured during the low-current stripping method corresponded to the coexistence of three pairs of the metallicintermetallic phases. This indicated that formation of Al-Pd alloys in a very controlled way and under technologically suitable conditions can be done at temperatures equal to and below 250ºC.