Direct Fabrication of Bimetallic Ti6Al4V+Al12Si Structures via Additive Manufacturing.

Ti6Al4V + Al12Si compositionally graded cylindrical structures were fabricated on a Ti6Al4V substrate using laser engineered net shaping (LENS™) process. LENS™ fabricated materials had two regions of Ti6Al4V + Al12Si compositions, a pure Al12Si, and a pure Ti6Al4V area. Microstructural changes were affected by both laser power and compositional variations. In addition, TiSi2 and Ti3Al phase formations were also identified in low and high laser power processed Ti6Al4V + Al12Si sections, respectively. Moreover, the high laser power processed Ti6Al4V + Al12Si section showed the highest hardness value of 685.6 ± 10.6 HV0.1, which was caused due to the formation of new intermetallic phases. This high hardness section exhibited brittle failure modes during compression tests, while the pure Al12Si sections showed ductile deformation. The maximum compressive strengths of Ti6Al4V + Al12Si compositionally graded material was 507.8 ± 52.0 MPa. Our results show that compositionally gradient bulk structures of Ti6Al4V and Al12Si can be directly manufactured using additive manufacturing, however, performances can vary significantly based on process parameters and compositional variations.