Diffusion Bonding of Ti6Al4V to Al2O3 Using Ni/Ti Reactive Multilayers

Abstract

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.

Joining Ti6Al4V to Alumina by Diffusion Bonding Using Titanium Interlayers

“…The adhesion strength between the Ti thin films and Al 2 O 3 was measured by a pull-off test using an apparatus as referred to in [45,46]; however, the substrate has a surface area three times higher than in the literature. The test consists of gluing the film deposited onto the alumina substrate to a rigid rod, following the curing time of the glue.…”

Joining of Ti6Al4V to Al2O3 Using Nanomultilayers

“…However, the conventional diffusion bonding process involves high temperature, pressure, and dwell time which causes thermal stress due to a mismatch in coefficient of thermal expansion (CTE) and thermal conductivity; consequently, cracks come up at the joint's interface, mainly during cooling [1]. Thus, several approaches have been developed to join dissimilar materials by diffusion bonding, like applying interlayers between the base materials to be joined [17][18][19][20][21][22][23][24]. The interlayer has a crucial role in reducing the temperature and pressure of the bonding process, and consequently, the thermal stress, besides increasing the contact area that favors achieving high strength joints.…”

Ta/Ti/Ni/Ceramic Multilayered Composites by Combustion Synthesis: Microstructure and Mechanical Properties

“…In view of their brittleness and chemical inertness, engineering ceramics are hard to join with metals [1]. The good joining of these dissimilar materials often requires the use of high temperature and pressure [1,2], pre-processing of surfaces to be joined, and the use of brazing alloys [3][4][5][6][7][8].…”

“…To date, multilayer cermet materials can be fabricated by several methods such as brazing [7][8][9][10], solid-state joining via friction-and laser-assisted welding [11][12][13], physical vapor deposition [14], spark plasma sintering [15], ceramic-metal diffusion bonding [4,5], melt infiltration [16,17]), and field-activated, pressure-assisted synthesis [18].…”

“…In this case, the main drawbacks are expensive facilities, the use of high pressure, a large duration of applied pressure, and the restricted configuration of resultant items [11][12][13][14][15]. The methods Metals 2022, 12, 38 2 of 16 of liquid-phase joining (ceramic-metal diffusion bonding, infiltration bonding) require the presence of the liquid phase, some certain optimal exposure time, and close contact between the adjoining surfaces [4,5,19]. Often lightweight metals (such as Al) are used as a transition layer between the metal and ceramic [17,20].…”