Enhanced surface composite coating on Ti811 alloy by laser cladding towards improved nano-hardness.

In this study, an enhanced surface composite coating with improved nano-hardness was successfully prepared on Ti811 alloy by means of laser cladding processing. The microstructure, phase composition, interface structure, and nano-hardness of the composite coating were systematically investigated. The results show that the Ti-based cladding coating contains CrTi 4 , Ti 2 Ni, TiC, α-Ti, and CeCrO 3. The single-track and multi-track overlapping regions of the coating form a fine metallurgical combination with the substrate and exhibit different microstructure characteristics due to differential cooling rates. The CrTi 4 -α-Ti transformation follows the Burgers orientation relationship, and the pinning effect of CeCrO 3 particles distributed at the grain boundaries effectively refines the CrTi 4 matrix. Moreover, the effective combination between interfaces ensures the improved nano-hardness of the coating. The results of this study provide a general guideline for studying the microstructure evolution and nano-hardness of composite coatings fabricated on titanium alloys using laser cladding technology or other additive manufacturing methods. [ABSTRACT FROM AUTHOR]