Study of Additive Manufactured Ti–Al–Si–Cu/Ti–6Al–4V Composite Coating by Direct Laser Metal Deposition (DLMD) Technique

Abstract

Direct laser metal deposition (DLMD) is an additive manufacturing technique that is favourable in industries such as aerospace, biomedical, sports and automotive. Its advanced three-dimensional printing via layer-by-layer additive of a material allows for high-dimensional accuracy of the manufacturing of a part, but the surface finishing is still a limitation for the technology. Complex geometrical parts can be manufactured or repaired by employing the technology. This study focuses on the DLMD of Ti–Al–Si–Cu-based composite coatings on Ti–6Al–4V substrate, with the processing parameters such as the laser power and scanning speed being varied, while the other parameters were invariant. The microstructural evolution was analysed, and its influence on the anisotropy of the mechanical properties, the hardness property, and the corrosion performance of the material was investigated. The results showed that at low laser power and scan speed of 900 W and 1.0 m/min of Ti–Al–13Si–6Cu, which had the highest addition of alloying content, the highest hardness and improvement on the substrate was achieved. Large intermetallics compounds were formed of which the grains varied between columnar and backbone-like structures. The composite coating with the best corrosion rate was Ti–Al–7Si–Cu at 1.305 × 10−3 mm/year.