Investigation of the properties of coatings produced by ESD method on AISI 1040 steel surface using Mo and Nb doped FeNiCrCoCu high-entropy alloys

High Entropy Alloys (HEAs) represent a new frontier in materials science and engineering, offering a unique combination of mechanical, physical, and chemical properties due to their complex multi-component composition. This distinctive blend of characteristics positions HEAs as promising candidates for a wide range of industrial applications, such as aerospace, automotive, and energy industries. Their superior properties, including improved structural integrity and enhanced corrosion resistance, open up new avenues for developing next-generation materials for extreme environments. This study explores the effect of molybdenum (Mo) and niobium (Nb) additions on the mechanical and physical properties of HEAs based on the FeNiCrCoCu system. Alloys with varying molar ratios of molybdenum and niobium (FeNiCrCoCuMox and FeNiCrCoCuNbx, where X = 0, 0.3, 0.6, and 0.9) were synthesized using the vacuum arc melting technique under a protective gas atmosphere with an inverted vacuum system to ensure optimal alloying conditions. The coatings were then applied to AISI 1040 steel substrates using the electro-spark deposition (ESD) method. Comprehensive characterization of the alloys was conducted through X-ray diffraction (XRD) for phase analysis, scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX) for microstructure and composition evaluation, and microhardness testing for mechanical property assessment. Coated samples underwent wear resistance testing using a standard electrochemical test, and corrosion resistance was evaluated using a 3.5% NaCl solution through an abrasion test. It was observed that the hardness of both the FeNiCrCoCuMox and FeNiCrCoCuNbx high entropy alloys increased as the amount of additive increased. The highest microhardness values were 654.36 HV0,1 for the FeNiCrCoCuMo0.9 alloy and 722.04 HV0,1 for the FeNiCrCoCuNb0,9 alloy. The incorporation of molybdenum and niobium significantly enhanced the phase stability and microhardness of the HEAs. A marked improvement in hardness and wear resistance was observed as the molar ratios of molybdenum and niobium increased. Additionally, the addition of these elements improved the wear resistance and overall mechanical performance of the coatings. These results highlight the potential of molybdenum-niobium doped HEA coatings for electrochemical corrosion and abrasion resistant applications and offer promising solutions for advanced industrial coatings requiring superior surface protection.