The influence of cooling rate, chromium and silicon addition on the structure and properties of AlCoCrFeNiSi high entropy alloys

Abstract AlCoCrFeNiSi high entropy alloys (HEAs) with variable chromium and silicon content (AlCoCrFeNiSi, AlCoFeNiSi, AlCoCr0.5FeNiSi0.5, AlCoFeNiSi0.5) were prepared by two different methods to determine the influence of cooling rate on the structure and properties of the alloys. The structure of the alloys was investigated using X-ray diffraction method and scanning electron microscopy. The possible formation of a single bcc/B2 phase was confirmed. The addition of chromium and silicon causes significant changes in the structure of the alloys, with new crystallographic phases being formed. The formation of Cr3Si intermetallic phases and segregation of iron was observed for the studied alloys. The magnetic properties were examined using a vibrating sample magnetometer and Mossbauer spectroscopy. The highest saturation magnetization was stated for alloys with a bcc/B2 one phase structure. The Mossbauer spectra confirmed, that ferromagnetic and paramagnetic phases occur in all studied alloys. The highest contribution from ferromagnetic phases was observed for the AlCoFeNiSi0.5 and AlCoCr0.5FeNiSi0.5 HEAs. Additionally, the corrosion resistance of the alloys was investigated in 3.5 % NaCl solution. It was noted, that the AlCoCrFeNiSi, in a form of plates, is characterized by the highest corrosion resistance.