Effect of microscale W elements on microstructure and properties of CoCrFeNiMnAl high entropy alloys

Abstract

High entropy alloys (HEAs) show better wear resistance and corrosion resistance than traditional alloys, which has gradually become a research hotspot in the field of metal materials. CoCrFeNiMnAlWx (x=0.12, 0.15, 0.19)high entropy alloys with different W content were prepared by metal thermal reduction. The effects of W addition on phase structure, microstructure and performance of CoCrFeNiMnAlWx high entropy alloy were investigated. The phase structure, microstructure and element distribution of the alloy were characterized by XRD, SEM and EDS. Surface performance tester and electrochemical workstation were adopted to detect corrosion resistance and wear resistance performance of CoCrFeNiMnAlWx high entropy alloy. Results show that the high entropy alloys with different W contents are both composed of BCC phases with two different lattice contents. There is no obvious change in the micro-tissue of the dendrites with the increase content of W. However, microstructure between dendrites changes significantly with the change of W content. The wear resistance and corrosion resistance have certain degree of improvement, the friction coefficient and wear rate of CoCrFeNiMnAlW0.19 alloy are 0.684 and 1.06×10-5 mm3/(N·m) respectively. The wear mechanism is converted from adhesive wear to the combination of adhesion wear and abrasive particle wear, and finally is transformed to friction wear. The wear resistance performance of CoCrFeNiMnAlWx high entropy alloy in 3.5% NaCl solution is increased with the increase of W content. Corrosion current density is decreased from 6.08×10-6 A/cm2 to 1.72×10-6 A/cm2, and the corrosion rate is gradually reduced.

Keywords

• high entropy alloy
• thermite reaction
• phase structure
• corrosion resistance
• wear resistance