Enable an interface having a chemical composition similar to one of the base materials, avoiding the formation of phases that will impair the service temperature and with characteristics that market the diffusion, enabling a lower in the diffusion bonding processing circumstances. Joining without the need of interlayer was also carried out utilizing the same parameters to evaluate the potential of those interlayers. The microstructural characterization in the joints’ interface was carried out by optical microscopy (OM), scanning electron microscopy (SEM), power dispersive X-ray spectroscopy (EDS), and electron backscatter diffraction (EBSD), even though the mechanical characterization was performed by nanoindentation tests across the joints’ interface and shear strength tests. two. Materials and Solutions 2.1. Base Materials Ti6Al4V alloy and polycrystalline Al2 O3 (purity of 99 ) have been purchased from Goodfellow in rods with 7 and 6 mm diameters, respectively. They were cut five mm in length, ground, and polished down to 1 diamond suspension and 0.03 silica applying regular metallographic process, then cleaned with deionized water, acetone, and ethanol in an ultrasonic bath and dried with heat blow air. The outcomes from the polishing have been assessed by optical microscopy (OM) (DM4000, Leica Microsystems, Wetzlar, Germany) and average roughness (Ra) with the surfaces was measured by profilometry (Perthometer SP4, with laser probe (Mahr Perthometer SP4, G tingem, Germany)). 2.2. Titanium Interlayer The titanium thin films were deposited onto the polished surfaces of alumina (substrate) by direct current magnetron sputtering applying a Ti (99.99 pure) target (150 mm 150 mm 6 mm thick). Following attaining a base pressure beneath five 10-4 Pa within the sputtering chamber, Ar was introduced (P 1.five 10-1 Pa). The substrate materials were cleaned by heating followed by Ar (present of 20 A) etching employing an ion gun. To prevent residual impurities from the substrates, assuring a very good adhesion among the substrate along with the Ti film, the total etching time employed was PF-06454589 Biological Activity elevated to 120 min greater than the usual situations. The deposition starts after the cleaning in the substrate is concluded, right after introducing a lot more argon into the sputtering chamber (4.0 10-1 Pa deposition pressure). The energy density applied to the Ti target was six.70 10-2 W m-2 . The Ti films were developed utilizing a substrate rotation speed of 23 rpm as well as a deposition time of 20 min to achieve a thickness of 1.0 . The titanium foil was purchased from Goodfellow using a purity of 99.6 , dimensions of 25 mm 25 mm, and thickness of five . For the joining experiments, the foil was reduce into rectangular parts with sizes of 7 mm 7 mm. 2.three. Adhesion The adhesion strength among the Ti thin films and Al2 O3 was measured by a pull-off test utilizing an apparatus as referred to in [45,46]; even so, the substrate includes a surface region three times larger than within the literature. The test consists of gluing the film deposited onto the alumina substrate to a rigid rod, following the curing time of your glue. Then, the set was fixed by the grips of a tensile test machine. The tensile tests were carried out below environmental conditions making use of a load cell of 500 N and a loading speed of 10 /min. The adhesion strength was estimated for 3 specimens to acquire the average value. two.four. Diffusion Bonding Ti6Al4V and Al2 O3 joining was performed within a tubular horizontal furnace (Termolab Electrical Furnace, Agueda, Portugal) below a