Aces show hardness and reduced Young modulus, which reflect the observed microstructure. The average shear strength values are comparable for all joints tested (52 14 MPa for the joint processed without the need of interlayer and 49 25 MPa for the joint processed with interlayer), which confirms that the usage of the Ti thin film improves the diffusion bonding of your Ti6Al4V alloy to alumina, enabling a reduce inside the joining temperature and time. Keyword phrases: diffusion bonding; thin film; titanium; Al2 O3 ; sputteringPublisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional PX-478 Description affiliations.1. Introduction Ti6Al4V is the most utilized commercial PF-06454589 Purity & Documentation titanium alloy due to its exceptional functionality and desirable properties, including high-temperature specific strength, low density, excellent creep, and corrosion resistance [1]. Combining this titanium alloy with advanced ceramics, e.g., alumina (Al2 O3 ), which has high thermal stability, excellent wear and corrosion resistance, and chemical inertness [2], might be interesting for applications in the medical, aircraft, nuclear and micro-electro-mechanical systems (MEMS) sectors [1,3]. On the other hand, obtaining sound joints with fantastic mechanical properties amongst titanium alloys and ceramic materials has been difficult because of their distinctive properties, e.g., thermal conductivity, coefficient of thermal expansion (CTE), and chemical properties. This mismatch of properties induces the formation of residual stresses at the joint’s interface in the course of cooling. Researchers have worked to improve understanding about the mechanisms that impact the joining of metals to ceramics [74]. Essentially the most reported technologies inside the literature withCopyright: 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is definitely an open access write-up distributed below the terms and situations of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ four.0/).Metals 2021, 11, 1728. https://doi.org/10.3390/methttps://www.mdpi.com/journal/metalsMetals 2021, 11,two ofregards to joining dissimilar components are brazing and solid-state diffusion bonding [157]. Brazing [188] is an attractive approach that consists of adding a filler metal amongst the base materials. Ag-based industrial alloys is often made use of effectively as brazing alloys given that they boost the reaction among metal and ceramic and improve wetting [29]. Even so, this brazing alloy produces an interface with a lower service temperature than the titanium alloy. Moreover, heterogeneous interfaces at microstructure and chemical composition level are formed, and post-processing heat therapies are necessary [30]. Diffusion bonding can obtain sound joints among dissimilar supplies, primarily when interlayers are applied to join the faying diffusion surfaces. In this case, cracks as a consequence of residual stress can be prevented [10,17,318]. Active components happen to be employed as interlayers, e.g., titanium, niobium, and zirconium [15,16]. Titanium could be the most employed interlayer; for example, it reacts with Al2 O3 by diffusion bonding resulting inside the formation of TiO, TiAl, and Ti3 Al [8]. The usage of interlayers in diffusion bonding may be a single option to reduce the bonding temperature, stress and time and make the approach more industrially desirable [39]. This may very well be much more vital in metal-ceramic joining, when the joint is subjected to thermal cycling or thermal shock, big strain concentrations might be introduced in components.