Microstructure and corrosion behavior of FeNiCoCrCu and FeNiCoCrMn high entropy alloys manufactured by powder metallurgy in different acid media

Abstract

FeNiCoCr, FeNiCoCrCu, and FeNiCoCrMn HEAs are manufactured by powder metallurgy. All samples powder was compacted at 430, 520, and 610 MPa with the uniaxial press. Then the compacted samples were sintered at 1150 °C and 1200 °C in a tube furnace under argon atmosphere. The microstructure and phase composition were identified by scanning electron microscope (SEM). Homogenous distribution in all samples due to the formation of a solid solution phase was observed respectively. FCC phase was obtained in the case of Cu as well as Mn. The density of the prepared alloys was estimated according to Archimedes principal which shows an improvement of the sample density by Cu addition more than that of Mn additions. Hardness was measured with Vickers microhardness and show an improvement in HEAs. The effect of Cu or Mn on the corrosion behavior was estimated by studying the effect of HNO3, H2SO4 and HCl acidic solutions for 120 h on the weight loss experiments and open circuit potential. The weight-loss experiment was established by immersing the samples into the acidic solution for corrosion test estimation. The solution was maintained at constant room temperature. Weight-loss of the samples was measured by an electronic balance. The FeNiCoCrCu HEA gets good performance of corrosion resistance. Weight-loss data resulted from the measured corrosion rates for FeNiCoCrCu HEA is only about 4.18973 mm/y in 5% HNO3 liquid, about 0.68807 mm/y in 10% H2SO4 liquid, 0.621103 mm/y in 5% HCl liquid and only about after 120 h.