Comparative study about the properties of in-situ synthesized TiN/Ti6Al4V sandwich structure materials by selective laser melting and laser directed energy deposition

Laser Additive Manufacturing (LAM) offers a versatile approach to fabricate composite materials, including heterogeneous and transition materials, characterized by exceptional mechanical properties. In this study, TiN/Ti6Al4V sandwich structural materials were prepared by the Selective Laser Melting (SLM) and Laser Directed Energy Deposition (LDED) processes, each in distinct environments featuring varying nitrogen-to-argon ratios. We conducted a comprehensive investigation, comparing the elemental diffusion, in-situ synthesis, microstructural characteristics, and mechanical properties of TiN/Ti6Al4V sandwich structural materials produced via these two processes. In both SLM and LDED processes, the in-situ synthesis of TiN from titanium and nitrogen atoms yielded robust metallurgical bonds with the Ti6Al4V matrix. The superior performance of TiN/Ti6Al4V sandwich structural materials achieved through LAM results from their laminar structure and the reinforcing effect of internal ceramic particles. Leveraging the combination of soft and hard layers within the sandwich structure, the tensile strength significantly surpasses that of homogeneous materials. Specifically, the sandwich structure materials synthesized through SLM and LDED attained impressive tensile strengths of 1303.1 MPa and 1155.1 MPa, respectively, alongside plastic deformations of 8.9% and 3.7%. This study highlights the potential of employing LAM in conjunction with controlled reactive atmospheres to fabricate new periodic heterogeneous materials in-situ, characterized by outstanding mechanical properties.