Boriding of diffusion bonded joints of pure nickel to commercially pure titanium

Diffusion bonding of pure nickel to commercially pure titanium was carried out at 900 °C for 1 h under 1 MPa in vacuum. After bonding process, samples were prepared by conventional metallographic methods and borided. Boriding was carried out in a solid medium consisting of Ekabor-Ni powders at 900 °C for periods of 1, 2, 3, 4, 6 and 8 h in vacuum of 2 × 10−3 Pa. The characterization of the diffusion zone formed in the bond interface and the boride layer formed on the surface of substrates were identified by scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS) and wave length dispersive spectroscopy (WDS). Good bonding was observed on all the samples. The presence of boride Ni2B and Ni3B formed on the surface of the substrate was confirmed by X-ray diffraction (XRD) analysis. Microhardness and thickness of boride layers were measured. Its hardness was found as 1300 ± 15 HV. Depending on the boriding process time, the thickness of coating layers ranged from 32 μm to 152 μm.