Improving mechanical properties of dissimilar TA3/L907A steel clad plates with multiple interlayers via hot-compression bonding

In this study, the TA3/L907A titanium-steel clad plates with or without interlayers were fabricated via HCB and the interfacial microstructure, and shear strength were investigated in detail. A reaction layer mixed by Fe-Ti interphases and TiC formed at the TA3/L907A interface and the formation of brittle intermetallic compounds (IMCs) severely deteriorated the interfacial properties, which resulted in a low shear strength of 192 MPa. To improve the shear strength, Ni foil, Nb foil, and Nb + Ni foils were respectively added as interlayer between TA3 and L907A. With interlayers, no visible Fe-Ti-C IMCs were detected at the interface, which suggests that interlayers effectively prohibited the inter-diffusion of these elements. Although Ni or Nb interlayer respectively elevated the interfacial shear strength to 333 MPa and 359 MPa, weak-bonded features such as lamellar Ni-Ti interphases and Fe2Nb IMC still existed, making cracks tend to initiate at these regions. Further adding Nb + Ni double interlayers achieved the highest shear strength of 422 MPa. The enhancement in property can be attributed to solid solution regions at both Ti/Nb and Ni/Steel interfaces without IMC or void, and the discontinuous distributed olive-like delta-Ni3Nb precipitation at the Nb/Ni interface.