Effects of Cu addition on the microstructure and properties of the Al–Mn–Fe–Si alloy

Heat exchanger materials with high strength and thin thickness are highly required due to the increasing demands of weight reduction and fuel economy of the automobile. In this work, 0.5 wt% Cu was added to an Al-1.5Mn-0.3Fe-0.6Si (wt.%) alloy to improve the strength. The microstructure, mechanical properties, and electrochemical properties of the tested alloys were systematically investigated. The results suggest that part of Cu is dissolved into the Al matrix, and the balance is incorporated into the Al(Mn,Fe)Si particles. Cu addition improves the strength at the expense of deteriorating the pitting corrosion resistance. On the one hand, the improved strength derives from enhanced solid solution hardening and increased nanoparticle strengthening. On the other hand, the incorporation of Cu in the Al(Mn,Fe)Si intermetallic particles increases the potential difference between the particles and the Al matrix, resulting in the deteriorated pitting corrosion resistance. [Display omitted] •Cu element exists in the form of Al(Mn,Fe)Si phase in Al-1.5Mn-0.3Fe-0.6Si-0.5Cu.•Cu addition produces finer grains and dense Al(Mn,Fe)Si nanoparticles.•Cu addition improves strength of Al-1.5Mn-0.3Fe-0.6Si.•Cu addition increases potential difference, so deteriorates corrosion resistance.