Additive manufacturing of micro/nano multiphase synergistically reinforced Ti-55Al-7.5Nb with a reticular boundary precipitate via direct laser deposition

Additive manufacturing, with features of micro-area metallurgy and rapid solidification, has become an effective way to construct complex components with high efficiency and production flexibility. Hereby, this study presents a micro/nano multiphase synergistically reinforced Ti-55Al-7.5Nb/Ti2AlN-Ti5Si3 metal-matrix composite (TiAl MMC) synthesized via direct laser deposition. The as-prepared TiAl MMCs exhibit homogeneously equiaxed grains and no cracks, compared with the coarse columnar microstructure and macro/micro cracks of Ti-55Al7.5Nb alloy. The grain size of the TiAl MMCs increases in the form of a parabola with increase of the laser power, and also increases from the bottom to the top along the building direction with fixed laser power. Precipitates of Ti2AlN and Ti5Si3 can alleviate the texture index, and thus facilitate an in situ production of isotropic MMCs. Meanwhile, TiAl MMCs feature excellent compressive and high-temperature (900 degrees C) tensile strength, resulting from the precipitates of rod-like Ti2AlN dispersed inside the grains, and the micro/nano-Ti5Si3 reticularly distributed at the grain boundaries (GBs). The micro/nano multiphase reinforcement could help guide the additive manufacturing of preparing reticular-boundary-reinforced cracks-free TiAl MMCs, which feature controllable microstructures and enhanced mechanical properties.

Automated summary

Additive manufacturing is an effective method for constructing complex components. A study has successfully synthesized a composite material with uniform microstructure and no cracks. The material exhibits excellent mechanical properties and is suitable for producing isotropic components.