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.