Abstract
In this work, the CoCrFeNiNbx (x: molar ratio, x = 0.45, 0.5, 0.75, and 1.0) high entropy alloy coatings were synthesized on a 304 stainless steel substrate by laser cladding to investigate the effect of Nb element on their microstructure, hardness, and wear resistance. The results indicated that in all of the CoCrFeNiNbx alloy coatings, two phases were found: One was a face-centered cubic (FCC) solid solution phase, the other was a Co1.92Nb1.08-type Laves phase. The microstructures of samples varied from hypoeutectic structure (x = 0.45 and 0.5) to hypereutectic structure (x = 0.75 and 1.0). The Vickers hardness of CoCrFeNiNbx alloy coatings was obviously improved compared with the substrate. The hardness value of the CoCrFeNiNb1.0 alloy coating reached to 590 HV, which was 2.8 times higher than that of the substrate. There was also a corresponding variation in wear properties with hardness evolutions. Wherein the hypereutectic CoCrFeNiNb1.0 alloy coating with the highest hardness exhibited the best wear resistance under the same wear condition, the dry wear test showed the wear mass loss of CoCrFeNiNb1.0 alloy coating was less than a third of the substrate. The high hardness and wear resistance properties were considered with the fine lamellar eutectic structure and proper combination of FCC and Laves phases.
Highlights
Conventional alloys are mainly based on one or two principal elements with the addition of several minor elements to improve the properties
high entropy alloys (HEAs) tended to form a simple solution phase, which attributed to a high entropy effect
The WMoNbTa, WMoNbTaV, TiZrHfNbMo, TaNbZrHf, and TiZrHfNbTa refractory HEAs [6,7,8,9] are composed of a single body centered cubic (BCC) phase
Summary
Conventional alloys are mainly based on one or two principal elements with the addition of several minor elements to improve the properties. The hardness and wear resistance of stainless steel can be improved by coating HEA on its surface. FeCoCrAlNi HEA coating [33] prepared by laser cladding on 304 stainless steel possessed high hardness, which was ~three times higher than that of the substrate. FeNiCoSiCrAlTi HEA coating [34] prepared by laser cladding on Q235 steel showed a much higher hardness (≈780 HV0.5 ). The microstructure and mechanical properties of CoCrFeNiNbx eutectic high entropy alloy The CoCrFeNiNbx (x ≥ 0.45) HEA coatings on 304 stainless steel substrate were prepared by laser cladding to investigate the effect of Nb element on their microstructure, hardness, and wear resistance
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