Effect of Bonding Temperature on the Joining of Ti-6Al-4V Alloy Using Cu Coatings and Sn Interlayers

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JMEPEG DOI: 10.1007/s11665-016-2429-1

Effect of Bonding Temperature on the Joining of Ti-6Al-4V Alloy Using Cu Coatings and Sn Interlayers Abdulaziz N. AlHazaa, Sultan H. AlGharbi, and Hiroshi Nishikawa (Submitted March 1, 2016; in revised form October 10, 2016)

Titanium alloy Ti-6Al-4V samples were bonded together using Cu coatings and Sn interlayers. The bonding of titanium samples was successful at various temperatures (700-950 °C) which are below the b-transus temperature of Ti-6Al-4V alloy. An applied uniaxial pressure of 1 MPa and a short bonding time of 15 min were selected as bonding parameters. Scanning electron microscope and energy-dispersive spectroscopy showed that the dissolution of Ti in the joint region increases with the increase in bonding temperature. X-ray diffraction analysis of the fractured surfaces revealed that Sn5Ti6, Sn3Ti5 and SnTi3 intermetallic compounds (IMCs) were formed and dominated the joint structure. The shear strengths of the bonds increase with the increase in bonding temperature and reaches a maximum of 478 MPa for bond made at 950 °C. The microhardness analysis of the fractured surfaces compared to the base alloy confirmed the presence of the IMCs. X-ray photoelectron spectroscopy (XPS) analysis showed the presence of Ti at the top surface of the fractured bonds made at 700 °C which confirmed a successful joint evolution even at the lowest bonding temperature used. Atomic force microscopy observations for bonds made at 700 and 950 °C coincide with the XRD and XPS analysis and were able to reveal the remaining Cu particles on the substrates. Keywords

bonding, Cu coatings, interlayers, Ti-6Al-4V alloy, x-ray diffraction

1. Introduction Titanium alloy Ti-6Al-4V covers about 60% of the use for the titanium industry. It is widely used in various applications. For example, in aerospace sector, the aircraft turbine engine and landing gear are made of Ti-6Al-4V alloy. Moreover, the titanium alloy is the major surgical implant in the medical field. It is used as a heat exchanger and a container for waste in nuclear industry (Ref 1-3). The evolution in the titanium application is due to its high specific strength, high corrosion resistance, high fatigue resistance and ability to withstand high temperature without creep. The titanium alloy is also a biocompatible material. The rapid development of advanced materials must be in parallel accompanied by intensive research and development for manufacturing processes such as joining technologies. Bonding of titanium alloys is a key process to repair many components including aero-engine components. Since the base components have already been designed in terms of their properties and geometries, it is a desire that these are retained during any bonding process. There are few advance joining processes done to join titanium alloys together such as laser welding (Ref 4, 5) and electron beam welding (Ref 6). However, such techniques cause melting of the titanium at the joints which resulted in large welding cracks and porosities at Abdulaziz N. A