Laser additive manufacturing of layered TiB2/Ti6Al4V multi-material parts: Understanding thermal behavior evolution

Selective laser melting (SLM) allows the fabrication of complex geometric shapes combined with improved functionalities and it has captured considerable attention for direct part production. While most studies conducted on the single materials, the multi-materials parts manufactured by this technology can offer more performance advantages of different materials to satisfy more demands in many engineering applications. Thus, TiB2/Ti6Al4V multi-material parts were fabricated to improve the properties of Ti6Al4V alloy components. In this study, a multilayer finite element model was proposed to investigate the complicated thermal behavior at the interface between the Ti6Al4V layer and TiB2 layer under varied process parameters. The temperature and temperature gradient distribution, remelting depth and liquid lifetime of the remolten pool at the as-fabricated Ti6Al4V layer during the SLM process of layered TiB2/Ti6Al4V multi-material parts were analyzed. The simulation results showed that the maximum temperature gradient was located at the interface. As the applied laser power increased from 300 W to 450 W, the maximum temperature gradient varied significantly, increasing from 24.920 degrees C/mu m to 37.754 degrees C/mu m while the maximum temperature gradient decreased slightly from 33.884 degrees C/mu m to 31.478 degrees C/mu m as the scan speed increased from 400 mm/s to 1000 mm/s. The interface temperature and liquid lifetime had an important influence on the wettability at the interface, which further impacted the metallurgical bonding at the interface. At the laser power of 400 W and the scan speed of 600 mm/s, a sound interfacial bonding could be achieved between the TiB2 layer and Ti6Al4V layer with a proper interface temperature of 2453 degrees C and liquid lifetime of 1.7 ms.