TiCp reinforced Ti6Al4V of follow-up synchronous electromagnetic induction-laser hybrid directed energy deposition: Microstructure evolution and mechanical properties

In this work, the follow-up synchronous electromagnetic induction-laser hybrid directed energy deposition (FEMI-DED) was proposed to prepare 10 wt% TiCp reinforced Ti6Al4V. Compared with DED, microstructure and mechanical properties of TiCp reinforced Ti6Al4V were improved by the Joule heat and Lorentz force of the electromagnetic field in FEMI-DED. Moreover, the effectiveness of surface induction heating in front and back of the molten pool was elucidated. The results show that in DED and FEMI-DED, primary TiC and eutectic TiC were both reinforced phase, and the primary TiC had the semi-coherent interface with α-Ti. In the DED, the primary TiC were coarse dendrite. The tensile strength and elongation were 893 ± 4.1 MPa and 0.70 ± 0.04 %, and the premature cracking of dendritic TiC was found by fracture analysis. But in the FEMI-DED, the quantity of refined dendritic primary TiC was decreased by ~26.2 %, and lots of granular TiC with the size of ~1.45 µm appeared. This is because the Joule heat reduced temperature gradient and increased growth rate, then the nucleation of granular TiC was promoted. Meanwhile, the Lorentz force increased dendrite fragmentation. By load-bearing strengthening of granular TiC, the tensile strength increased to 960 ± 11.5 MPa with the elongation of 0.73 ± 0.04 %.