1. Microstructure evolution and solidification mechanism of CoCrFeNiMoNb high entropy alloy coating by laser cladding.
- Author
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Wu, Tao, Yu, Litao, Shuai, Xu, Fang, Yihang, Zheng, Xiaofeng, Zhang, Lingfeng, Xue, Yanpeng, Lu, Yonghao, and Luan, Benli
- Subjects
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MICROSTRUCTURE , *SOLIDIFICATION , *MARANGONI effect , *CRYSTAL grain boundaries , *LASERS , *BAINITIC steel - Abstract
Because of its excellent wear resistance and corrosion resistance, CoCrFeNi-based HEA has been selected as the coating prepared on steels to improve its service life. This paper presents single-track CoCrFeNiMo 0.2 Nb 0.2 HEA cladding layers fabricated at different laser scanning speeds on an AISI H13 steel substrate. The grain morphology, microstructure and elemental distribution are illustrated. The phase constituents of the fusion zone (FZ) and middle section of the coatings were analyzed. The outcomes of this research showed that as the laser scanning speed increased, the grains in the cladding layers were refined, while the variation in the Fe elemental content first increased and then decreased. In the FZ, Mo and Nb, as strong carbide-forming elements, preferentially combined with the carbides in the substrate, forming a new (Mo)NbC phase with a grain size of 600 nm at the retained austenite grain boundary. During the process of laser cladding, the thermal Marangoni flow of multiple principal components and the solidification of the molten pool, which are influenced by the scanning speed, determine the microstructure of the (Mo)NbC in the FZ and eutectic in the in-between section of the cladding layer. The illustration of the microstructure evolution and solidification mechanism in this study can provide a foundation for the potential applications of HEA coatings. [Display omitted] • The single-track CoCrFeNiMo 0.2 Nb 0.2 HEA cladding layers were prepared on an AISI H13 steel. • The Mo, Nb elements in fusion zone prefer to form (Mo)NbC with a size of 600 nm at the retained-austenite grain boundaries. • The microstructure evolution from substrate to cladding layer is austenite, retained-austenite + (Mo)NbC, and eutectic. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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