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• A Ti-based reinforced Ti 2 Ni/Ti 2 S coating was fabricated by laser cladding on TC4 alloy. • The thermodynamic characteristics of the laser molten pool were described. • The orientation relationships of β-Ti and TiC were determined. • The microhardness and wear resistance of the deposited coating were improved. In this study, a Ti 2 Ni/Ti 2 S reinforced Ti-based composite coating was fabricated using laser cladding to improve the mechanical properties of TC4 alloy. The results show that the high temperature (>3000 K) of the molten pool ensures the effectiveness of the deposited coating and the thermodynamic conditions for in situ reactions. The phases consisted of β-Ti, Ti 2 Ni, Ti 2 S, TiC, and WC. Furthermore, β-Ti nucleated and grew with TiC as heterogeneous cores due to their orientation relationships of β-Ti{1 0 0}//TiC{1 1 0} and β-Ti{1 1 0}//TiC{1 1 1}. As a result, the microhardness of the coating was 2.30 times higher than the substrate, and the wear volume decreased by 20.23 % compared to the substrate. [ABSTRACT FROM AUTHOR]

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]