Microstructure and properties of TiNiTa shape memory alloy coating by laser additive manufactured on the surface of Ti6Al4V

This study successfully synthesized a TiNiTa shape memory coating on Ti6Al4V(TC4) substrate using laser additive manufacturing. A systematic study was conducted on the prepared TiNiTa shape memory alloy coating. The results revealed that the alloy coating consists of fine dendritic grains with uniform elemental distribution. The coating exhibited a microhardness of 867.4 HV, with wear resistance 42 times higher than that of the substrate, and its tribological performance significantly surpassed that of the substrate. This enhancement was attributed to the good toughness and unique superelastic characteristics of the TiNiTa shape memory alloy coating. Numerical simulations demonstrated that the laser heat source model aligned well with experimental results, achieving a maximum molten pool temperature of 2757.4 °C. Additionally, the energy density of the laser equipment was found to be positively correlated with the coating dilution rate during preparation, which provided a basis for process optimization in laser additive manufacturing. Meanwhile, as the full-immersion time prolonged and the soaking temperature increased, the TiNiTa coating displayed minimal mass loss and corrosion rate. It is inferring that the enhanced corrosion resistance is due to the formation of a protective passivation film when the coating is immersed in the corrosive solution. The aforementioned findings offer theoretical support for optimizing laser additive manufacturing process parameters and lay a foundation for further improving coating performance.