Metallurgical aspects of the corrosion resistance of 7000 series aluminum alloys – a review

Abstract

This article contains a review of selected studies conducted in the field of corrosion resistance of precipitation-hardenable 7000 series aluminum alloys. In particular, it discusses the effect of heat treatment and the role of thus formed microstructure on the corrosion behavior of these alloys. The article presents the three types of corrosion that occur most commonly in this group of materials in the context of their microstructure. It points to the importance of the chemical composition of a 7000 alloy, including the precipitates present in the microstructure, for the development of corrosion. The aluminum solid solution can act as an anode or cathode in relation to intermetallic particles. Such corrosion features may result in the destruction of the surfaces of elements made of the 7000 series aluminum alloy. It also raises the issue of the mechanism of corrosive destruction of the aluminum solid solution, which is connected with a crystallographic attack. In the case of this process, the nature of the micro-pits formed as a result of their local dissolution is related to the privileged dissolution of specific crystallographic planes and directions.