Effects of nickel content on the microstructure, microhardness and corrosion behavior of high-entropy AlCoCrFeNix alloys

M López Ríos,J C Mirza Rosca,V Geanta,I Boerasu,P P Socorro Perdomo,I Voiculescu,V Crăciun

doi:10.1038/s41598-020-78108-5

Abstract

In this study the effect of three different nickel concentration on the microstructure, hardness and corrosion properties of high entropy alloys (HEAs) from AlCrFeCoNi system as an alternative material for medical instruments fabrication was investigated. The analyzed HEAs were AlCrFeCoNix obtained by vacuum arc remelting from high purity raw materials and having nickel atomic ratio x = 1.0, 1.4 and 1.8. The microscopy examination revealed the dendritic morphology for the reference alloy (AlCrFeCoNi) and that the extent of the interdendritic areas increased with the concentration of nickel while Cr was more segregated in the interdendritic areas than in dendrites. Hardness values decreased as the percentage of nickel increased due to the dissolution of the precipitates in a nickel-rich matrix and consequently the formation of continuous solid solutions. The corrosion properties of the synthesized HEAs were evaluated using a potentiodynamic polarization method. The alloys were immersed in Simulated Body Fluid during one week and the corrosion parameters were recorded. The low corrosion rates, low corrosion currents and high polarization resistance attest the good stability of these HEAs in simulated biological environment indicating their possible use for surgical and dental instruments.

Highlights

Classic metallic alloys generally contain one metal in a high proportion, called the base metal, and very rarely two metals in similar proportions
Many interesting topics have been explored, only few studies deal with corrosion properties of this high-entropy alloy, in general depending of fabrication method: if is synthesized by laser additive[16], by electrospark process[17] and by spark plasma sintering with pre-alloy powders obtained through gas atomization[18]
The different concentrations of the alloying elements involves the morphology of the phases

Summary

Introduction

Classic metallic alloys generally contain one metal in a high proportion, called the base metal, and very rarely two metals in similar proportions. In this study the effect of three different nickel concentrations on the microstructure, hardness and corrosion properties of high entropy alloys from AlCrFeCoNi system has been investigated. As the Ni content increases in the Ni1.4 alloy, the appearance of acicular phases is observed (Fig. 1e).

Results

Conclusion