Effects of interrupted aging on the intergranular corrosion behavior of Al–Cu–Mg–Ag heat-resistant alloy

Abstract

Purpose The purpose of this study is to research the effects of interrupted aging on the corrosion behavior of Al–Cu–Mg–Ag heat-resistant alloy by means of intergranular corrosion (IGC) testing, potentiodynamic polarization combined with optical microscopy and transmission electron microscopy. Design/methodology/approach The results show that the IGC began on the grain boundaries and continued along the grain boundary. The corrosion resistance property of Al–Cu–Mg–Ag alloy was enhanced by interrupted aging. The precipitations of the interrupted aged sample both in the grains and on the grain boundaries were fine, and the chain-like phases on the grain boundary were distributed nearly continuously. Findings The corrosion resistance of Al–Cu–Mg series Al alloy with equilibrium phase (Al2Cu) is notably determined by precipitation-free zone (PFZ) as the self-corrosion potentials of (Al2Cu), PFZ and the matrix satisfied the relation EPFZ < Eθ<EMatrix. Originality/value The connections of the PFZ on both sides of the grain boundary decreased the corrosion resistance of Al–Cu–Mg–Ag alloy treated by the single aging.