Cu10Sn to Ti6Al4V bonding mechanisms in laser-based powder bed fusion multiple material additive manufacturing with different build strategies

Additive manufacturing of titanium alloy (TiA) – copper alloy (CuA) multiple material components poses many challenges due to the significant differences in their material properties. No previous studies have been found to investigate bonding characteristics of TiA-CuA interface fabricated in the build order of TiA→CuA (i.e. TiA first) via laser powder bed fusion (L-PBF). Here we show the interface characteristics of TiA→CuA under different build strategies. We have found that direct bonding causes CuA to delaminate from TiA due to the thin Ti-Cu reaction zone (< 10 µm). Remelting of the interface zone and a few CuA layers close to the interface zone makes the CuA melt pool at the interface to enter a keyhole mode to achieve more Ti-Cu mixing, leading to sound bonding between the materials. The functionally graded material (FGM) causes Ti-Cu brittle phases with a hardness > 1000 Hv and leads to cracks and the separation of CuA part from preprinted TiA part. The bonding mechanisms involved in the different scenarios are proposed.