Laser directed energy deposition of Ti6Al4V/M50 steel bimetals: comparative study of Nb/Cu and Nb/Cu/Ni interlayers

Résumé fourni par la source

The titanium/steel bimetal combines the advantages of titanium alloy’s low density and steel’s high wear resistance, demonstrating potential applications in aerospace fields. However, research on laser directed energy deposition for fabricating such materials remains limited. This study employed laser directed energy deposition technology to prepare Ti6Al4V/M50 steel bimetal using Nb/Cu and Nb/Cu/Ni as transition layers, systematically comparing their effects on interface microstructure, phase composition, grain size, and mechanical properties. Results indicated that the Nb/Cu transition layer exhibited insufficient elemental diffusion at the interface, with pure Cu layer showing an average hardness of 70 HV and shear strength of 191.9 ± 11.0 MPa. In contrast, the Nb/Cu/Ni transition layer exhibited enhanced solid solution strengthening through Ni diffusion within the Cu layer. This diffusion process generated blocky NbNi 3 phases, dispersed Ni 6 Nb 7 nanoparticles at the Nb/Cu interface, and (Cu, Ni) solid solution formation in the Cu-rich region, collectively improving hardness (120 HV) and shear strength (291.4 ± 52.2 MPa). The study confirms that the Nb/Cu/Ni transition layer effectively improves interfacial bonding quality and joint strength in titanium/steel bimetal systems, providing experimental evidence for relevant engineering applications.

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