Microstructural evolution, mechanical and wear properties, and corrosion resistance of as-cast CrFeNbTiMox Refractory high entropy alloys

Abstract

In this paper, a series of novel CrFeNbTiMox (x=0.2, 0.4, 0.6, 0.8, 1) refractory high entropy alloys (RHEAs) were fabricated. The effects of different Mo content on the microstructure evolution, mechanical properties, wear and corrosion resistance were investigated. As the increasing of Mo content, the microstructure of the alloy was BCC phase (body-centered cubic Im3m), C14-Laves (P63/MMC) and C15-Laves (Fd3m) as revealed by XRD and electron back-scattered diffraction (EBSD). Apart from the disordered BCC phase, another ordered B2 phase (Pm3m) also appeared in RHEAs. The final experiment showed: Uniaxial compression and microhardness tests revealed that the compressive strength and Vickers microhardness of the RHEAs were in the range 350–800 MPa and 800–931 HV, respectively, and increased with increasing Mo content. Electrochemical tests in a 3.5 wt.% NaCl solution showed that the RHEAs exhibited a significantly corrosion resistance. The sample Mo1 exhibited the highest Ecorr and smallest icorr and therefore the best corrosion resistance. The wear rate and coefficient of friction of the RHEAs increased with increasing Mo content. The sample Mo1 exhibited the lowest wear rate and coefficient of friction of 0.6 mg and 0.6255, respectively. The RHEAs synthesized in this work, especially Mo1, exhibited a high strength and excellent corrosion and wear resistance. Therefore, they have immense potential for various engineering applications.