The preparation of gradient titanium alloy through laser deposition

Functionally gradient materials (FGMs) with continuous variation in composition or microstructure can realize gradient properties in different positions of the same component. The layer-by-layer laser deposition additive manufacturing is one of the most promising technologies that prepare FGMs with gradient properties. The present study is focused on the preparation of gradient titanium alloy by laser depositing Ti2AlNb powders on the substrate of a near-α high temperature titanium alloy. The microstructure, composition, and micro-hardness of prepared gradient titanium alloy with and without transition layer were compared and analyzed. Results show that an obvious bonding interface with variant microstructure morphology and element contents formed during directly deposited Ti2AlNb powders on near-α titanium alloy substrate and the bonding interface exhibits higher micro-hardness than the substrate and the deposited zone. However, the microstructure and the element exhibit gradient distribution characteristics along the deposition direction after adding the mixed powders of both two alloys as intermediate transition layers between the near-α titanium alloy and the Ti2AlNb alloy. The gradient distributed micro-hardness from the substrate to the top deposited zone sufficiently demonstrates the feasibility of obtaining gradient properties of gradient titanium alloy with composition transition layer during laser depositing.