OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 25 No. 3 2023 The addition of 5 % and 10 % CrB resulted in an increase in the volume of worn material despite an increase in the average microhardness of the coatings. Probably, the decrease in the wear resistance is associated with the formation of lamellar eutectic. During testing, the lamellar eutectic was degraded. The fracture products located in the contact zone between the counterbody and the specimen induced abrasive wear of the coating material (fig. 10e). With a higher content of chromium boride in the composition of the coatings, the proportion of the plastic matrix decreases, and the average microhardness of the coatings increases. As a result, the abrasive wear mechanism appears to a lesser extent. Conclusions With reference to the conducted research, it was established that regardless of the amount of CrB powder added to the surfacing mixture, a metal matrix based on the fcc solid solution was formed in the coatings. The appending of 5 % and 10 % CrB led to the formation of a lamellar eutectic consisting of (Cr,Mn,Fe)2B crystals and the fcc solid solution. An increase in the amount of CrB in the surfacing mixture to 20 % or more resulted in the formation of a metal matrix depleted in chromium, primary CrB-type borides, as well as a skeleton eutectic consisting of (Ni,Co,Mn)2B and the fcc solid solution in the structure. An increase in the CrB fraction in the powder mixture from 0 to 30 % contributed to an increase in the average microhardness of coatings from 192 to 1,141 HV0.1. Wear resistance testing of the coatings under investigation according to the ball-on-flat scheme revealed an adhesive wear mechanism. The appending 5 % and 10 % CrB led to additional abrasive wear by particles of eutectic borides and, accordingly, to a decrease in the wear resistance of coatings. Increasing the CrB content in the surfacing mixture to 20 % and 30 % contributed to an increase in the wear resistance of coatings by a factor of 3 and 6 compared to a material without CrB additions. Thus, the amount of worn material was reduced from 0.61 mm3 (0 % CrB) to 0.17 mm3 (20 % CrB) and 0.1 mm3 (30 % CrB), respectively. References 1. Yeh J.W., Chen S.K., Lin S.J., Gan J.Y., Chin T.S., Shun T.T., Tsau C.H., Chang S.Y. Nanostructured high-entropy alloys with multiple principal elements: novel alloy design concepts and outcomes. Advanced Engineering Materials, 2004, vol. 6, iss. 5, pp. 299–303. DOI: 10.1002/adem.200300567. 2. Cantor B., Chang I.T.H., Knight P., Vincent A.J.B. Microstructural development in equiatomic multicomponent alloys. Materials Science and Engineering: A, 2004, vol. 375–377, pp. 213–218. DOI: 10.1016/j.msea.2003.10.257. 3. Tsai M.H., Yeh J.W. High-entropy alloys: a critical review. Materials Research Letters, 2014, vol. 2, iss. 3, pp. 107–123. DOI: 10.1080/21663831.2014.912690. 4. George E.P., Raabe D., Ritchie R.O. High-entropy alloys. Nature Reviews Materials, 2019, vol. 4, iss. 8, pp. 515– 534. DOI: 10.1038/s41578-019-0121-4. 5. Steurer W. Single-phase high-entropy alloys – A critical update. Materials Characterization, 2020, vol. 162, pp. 1–17. DOI: 10.1016/j.matchar.2020.110179. 6. Zhang Y., Zuo T.T., Tang Z., Gao M.C., Dahmen K.A., Liaw P.K., Lu Z.P. Microstructures and properties of highentropy alloys. Progress in Materials Science, 2014, vol. 61, pp. 1–93. DOI: 10.1016/j.pmatsci.2013.10.001. 7. Duchaniya R.K., Pandel U., Rao P. Coatings based on high entropy alloys: An overview. Materials Today: Proceedings, 2021, vol. 44, pp. 4467–4473. DOI: 10.1016/j.matpr.2020.10.720. 8. Li W., Liu P., Liaw P.K. Microstructures and properties of high-entropy alloy films and coatings: a review. Materials Research Letters, 2018, vol. 6, iss. 4, pp. 199–229. DOI: 10.1080/21663831.2018.1434248. 9. Jiang P.F., Zhang C.H., Zhang S., Zhang J.B., Chen J., Liu Y. Fabrication and wear behavior of TiC reinforced FeCoCrAlCu-based high entropy alloy coatings by laser surface alloying. Materials Chemistry and Physics, 2020, vol. 255, pp. 1–10. DOI: 10.1016/j.matchemphys.2020.123571. 10. Guo Y., Li C., Zeng M., Wang J., Deng P., Wang Y. In-situ TiC reinforced CoCrCuFeNiSi0.2 high-entropy alloy coatings designed for enhanced wear performance by laser cladding. Materials Chemistry and Physics, 2020, vol. 242, pp.1– 9. DOI: 10.1016/j.matchemphys.2019.122522. 11. Gu Z., Xi S., Sun C. Microstructure and properties of laser cladding and CoCr2.5FeNi2Tix highentropy alloy composite coatings. Journal of Alloys and Compounds, 2020, vol. 819, pp. 1–10. DOI: 10.1016/j. jallcom.2019.152986.
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