Improved microstructure and wear resistance of (CoCrNi)82Al9Ti9 cladding layers via extreme high-speed laser cladding

Compared with conventional laser cladding (CLC), extreme high-speed laser cladding (EHLA) offers substantially enhanced cladding efficiency and improved coating properties. In this study, (CoCrNi)82Al9Ti9 high-entropy alloy (HEA) coatings were prepared via CLC and EHLA. The coatings were also characterized and tested. Results indicated that the thickness of the EHLA coating was 261.9 mu m, the microstructure of the cladding layer consisted of alternating lamellar FCC matrix and strengthening phases (B2 and L21), and the average grain size was 5.3 mu m. The EHLA coating has approximately three times more strengthening phases than the CLC coating. Thus, the microhardness of the EHLA coating in the range of 25-650 degrees C is approximately twice that of the CLC coating, and the wear rate of the former at 650 degrees C is 61 % lower than that of the latter. EHLA markedly improves the wear resistance of HEA coating at room temperature and 650 degrees C.