Structure and selected properties of Al–Cr–Fe alloys with the presence of structurally complex alloy phases

The aim of the study was to supplement the data on the Al 65 Cr 20 Fe 15 alloy with binary phase structure and the Al 71 Cr 24 Fe 5 alloy with multiphase structure prepared with two different cooling rates from the liquid state. The presence of the structurally complex Al 65 Cr 27 Fe 8 phase was confirmed by neutron diffraction, scanning electron microscopy with the analysis of chemical composition and transmission electron microscopy. Additionally, the Al 8 Cr 5 phase with γ-brass structure was identified for Al 71 Cr 24 Fe 5 alloy in both cooling rates from the liquid state. Due to the interesting features of structurally complex alloys, the wear resistance, magnetic properties, and corrosion products after performing electrochemical tests were examined. Based on pin-on-disc measurements, a lower friction coefficient was observed for the Al 65 Cr 20 Fe 15 alloy (µ ≈ 0.55) compared to the Al 71 Cr 24 Fe 5 multiphase alloy (µ ≈ 0.6). The average hardness of the binary phase Al 65 Cr 20 Fe 5 alloy (HV 0.1 = 917 ± 30) was higher compared to the multiphase Al 71 Cr 24 Fe 5 alloy (HV 0.1 = 728 ± 34) and the single phase Al–Cr–Fe alloys described in the literature. Moreover, the beneficial effect of rapid solidification on hardness was demonstrated. The alloys Al 65 Cr 20 Fe 15 and Al 71 Cr 24 Fe 5 showed paramagnetic behavior, however rapidly solidified Al 71 Cr 24 Fe 5 alloy indicated an increase of magnetic properties. The studied alloys were characterized by the presence of passive layers after electrochemical tests. A higher amount of oxides on the surface of the Al 71 Cr 24 Fe 5 alloy was recorded due to the positive effect of chromium on the stabilization of the passive layer.