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

Abstract

The aim of the study was to supplement the data on the Al65Cr20Fe15 alloy with binary phase structure and the Al71Cr24Fe5 alloy with multiphase structure prepared with two different cooling rates from the liquid state. The presence of the structurally complex Al65Cr27Fe8 phase was confirmed by neutron diffraction, scanning electron microscopy with the analysis of chemical composition and transmission electron microscopy. Additionally, the Al8Cr5 phase with γ-brass structure was identified for Al71Cr24Fe5 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 Al65Cr20Fe15 alloy (µ ≈ 0.55) compared to the Al71Cr24Fe5 multiphase alloy (µ ≈ 0.6). The average hardness of the binary phase Al65Cr20Fe5 alloy (HV0.1 = 917 ± 30) was higher compared to the multiphase Al71Cr24Fe5 alloy (HV0.1 = 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 Al65Cr20Fe15 and Al71Cr24Fe5 showed paramagnetic behavior, however rapidly solidified Al71Cr24Fe5 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 Al71Cr24Fe5 alloy was recorded due to the positive effect of chromium on the stabilization of the passive layer.