Effect of refractory elements on boronizing properties of the CoCrFeNi high entropy alloy

Abstract

The chemical composition of high entropy alloys (HEAs) is complex and HEAs contain a wide variety of alloying elements. The aim of this study was to investigate the effect of refractory elements (Ti, Nb) content on the boronizing behavior of CoCrFeNi alloys. The X-ray Diffractometer (XRD) analysis showed that boride layers containing Ni2Si, FeB, Fe2B, Co2B and Cr5B3 phases. In addition to this, TiB2 and NbB2 phases were detected on CoCrFeNiTi and CoCrFeNiNb alloys, respectively. The content of Ti and Nb in alloys resulted in decrease in boride layer (BL) thickness, which was measured for, CoCrFeNi, CoCrFeNiTi and CoCrFeNiNb as 70 mu m, 7 mu m and 4.3 mu m respectively. Si atoms which were accumulated close to BL and Si atoms were not transferred into substrates. Therefore, it was concluded that the BL prevented the transition of Si atoms. The interface of the BL having smooth morphology was identified on alloys.