This paper aims to investigate the diffusion bonding of Ti6Al4V to Al2O3. The potential of the use of reactive nanolayered thin films will also be investigated. For this purpose, Ni/Ti multilayer thin films with a 50 nm modulation period were deposited by magnetron sputtering onto the base materials. Diffusion bonding experiments were performed at 800 °C, under 50 MPa and a dwell time of 60 min, with and without interlayers. Microstructural characterization of the interface was conducted through scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS). The joints experiments without interlayer were unsuccessful. The interface is characterized by the presence of a crack close to the Al2O3 base material. The results revealed that the Ni/Ti reactive multilayers improved the diffusion bonding process, allowing for sound joints to be obtained at 800 °C for 60 min. The interface produced is characterized by a thin thickness and is mainly composed of NiTi and NiTi2 reaction layers. Mechanical characterization of the joint was assessed by hardness and reduced Young’s modulus distribution maps that enhance the different phases composing the interface. The hardness maps showed that the interface exhibits a hardness distribution similar to the Al2O3, which can be advantageous to the mechanical behavior of the joints.

This work aims to investigate the joining of Ti6Al4V alloy to alumina by diffusion bonding using titanium interlayers: thin films (1 µm) and commercial titanium foils (5 µm). The Ti thin films were deposited by magnetron sputtering onto alumina. The joints were processed at 900, 950, and 1000 °C, dwell time of 10 and 60 min, under contact pressure. Experiments without interlayer were performed for comparison purposes. Microstructural characterization of the interfaces was conducted by optical microscopy (OM), scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS), and electron backscatter diffraction (EBSD). The mechanical characterization of the joints was performed by nanoindentation to obtain hardness and reduced Young’s modulus distribution maps and shear strength tests. Joints processed without interlayer have only been achieved at 1000 °C. Conversely, joints processed using Ti thin films as interlayer showed promising results at temperatures of 950 °C for 60 min and 1000 °C for 10 and 60 min, under low pressure. The Ti adhesion to the alumina is a critical aspect of the diffusion bonding process and the joints produced with Ti freestanding foils were unsuccessful. The nanoindentation results revealed that the interfaces show hardness and reduced Young modulus, which reflect the observed microstructure. The average shear strength values are similar for all joints tested (52 ± 14 MPa for the joint processed without interlayer and 49 ± 25 MPa for the joint processed with interlayer), which confirms that the use of the Ti thin film improves the diffusion bonding of the Ti6Al4V alloy to alumina, enabling a decrease in the joining temperature and time.