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• Generation of hard phases and grain refinement in enhanced bionic units. • Bionic unit samples have good hard-soft alternating bionic structure. • Quantitative relation between distribution spacing and wear resistance is obtained. • Hard-soft bionic structure improves wear resistance by altering the wear pattern. • Adjusting the distribution spacing has a more positive effect on wear resistance. In this study, the biomimetic unit samples (BUSs) of hard-soft structure with different distribution spacings were successfully prepared by laser quenching biomimetic processing technique (LQBPT). Firstly, the microstructure, microhardness, tribological properties and wear surfaces were investigated. The BUSs had randomly oriented martensite and M 7 C 3 , and the grains were refined, resulting in favorable hard-soft structures. Compared to the untreated samples, the BUS at distribution spacing of 3 mm had excellent wear resistance. Its average friction coefficient and weight loss were reduced by 17.95 % and 40.0 %, respectively. Then, it was investigated the quantitative relationship between the distribution spacing and the wear resistance and its wear resistance mechanism. This improved wear resistance was attributed to hard-soft biomimetic structure. [ABSTRACT FROM AUTHOR]

• La 2 O 3 improved the temperature gradient and reduces crack susceptibility. • La 2 O 3 promoted nucleation and grain refinement and increases dislocation density. • La 2 O 3 doping increased the hardness of the coating and improved the wear pattern. In this study, CoCrFeNiMoSi and CoCrFeNiMoSi + 0.5 % La 2 O 3 High entropy alloy (HEA) coatings were prepared by laser cladding. The microstructure was consisted mainly of body-centered cubic structure, face-centered cubic structure and intermetallic compounds of Si. The addition of rare earth La 2 O 3 resulted in the refinement and uniformity of the CoCrFeNiMoSi + 0.5 % La 2 O 3 HEA coating grains, leading to an increase in microhardness from 430 HV to 520 HV. Additionally, the friction coefficient decreased by 0.15 and the wear rate decreased by 2/3. These findings indicate that the appropriate addition of La 2 O 3 has significant potential in enhancing the friction and wear performance of HEA coatings. [ABSTRACT FROM AUTHOR]

The AlCoCrFeNi high-entropy alloy coatings were prepared by laser cladding (LC) and reprocessed by laser remelting (LR). Laser remelting caused cracks on the coating surface, but the cracks of boronized laser remelting (LR-B) coating were significantly suppressed. Compared to the LR coating, the microhardness of the LR-B coating increased from 643 HV to 1008 HV, the friction coefficient decreased from 0.55 to 0.45, and the self-corrosion potential increased by 134 mV. The crack elimination contributed to the transition of 25% of the BCC phase to the FCC phase. The property enhancement was mainly due to the fine grain strengthening, dislocation strengthening, and Cr 2 B reinforced particles as reinforced phase. [Display omitted] • A trace amount of boron was doped in the protective gas during laser remelting. • The cracks of the boronized laser remelting (LR-B) coating were significantly suppressed. • With the addition of boron, the FCC phase and Cr 2 B were formed. • The Cr 2 B second-phase strengthening increased microhardness and wear resistance. • The Cr 2 B particles in the LR-B coating resulted in excellent corrosion resistance. To avoid cracking of the AlCoCrFeNi high-entropy alloy (HEA) coating during laser remelting (LR), a trace amount of boron (B) was doped in the protective gas. Compared to the LR coating, the cracks of the boronized laser remelting (LR-B) coating were significantly suppressed, the microhardness increased from 643 HV to 1008 HV, the friction coefficient decreased from 0.55 to 0.45, and the self-corrosion potential increased by 134 mV. The crack elimination mainly contributed to the transition of 25 % of the BCC phase to the FCC phase, and the property enhancement was due to the fine grain strengthening, dislocation strengthening, and Cr 2 B reinforced particles generation. This novel finding can be applied to other BCC structure HEA coatings for macroscopic crack control and optimization of wear and corrosion resistances. [ABSTRACT FROM AUTHOR]