Diffusion Bonding of Ti2AlNb Alloy and High-Nb-Containing TiAl Alloy: Interfacial Microstructure and Mechanical Properties

Abstract

In this study, reliable Ti2AlNb/high-Nb-containing TiAl alloy (TAN) joints were achieved by diffusion bonding. The effects of bonding temperature and holding time on the interfacial microstructure and mechanical properties were fully investigated. The interfacial structure of joints bonded at various temperatures and holding times was characterized by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and X-ray diffraction (XRD). The results show that the typical microstructure of the Ti2AlNb substrate/O phase/Al(Nb,Ti)2 + Ti3Al/Ti3Al/TAN substrate was obtained at 970 °C for 60 min under a pressure of 5 MPa. The formation of the O phase was earlier than the Al(Nb,Ti)2 phase when bonding temperature was relatively low. When bonding temperature was high enough, the Al(Nb,Ti)2 phase appeared earlier than the O phase. With the increase of bonding temperature and holding time, the Al(Nb,Ti)2 phase decomposed gradually. As the same time, continuous O phase layers became discontinuous and the Ti3Al phase coarsened. The maximum bonding strength of 66.1 MPa was achieved at 970 °C for 120 min.

Microstructure and properties of TiAl/Ti2AlNb joint with TC1 intermediate layer obtained by spark plasma sintering diffusion welding

“…Ti2AlNb alloy is an orthogonal O-phase alloy formed by adding Nb elements to α2-Ti3Al alloy, which further improves its machinability and room temperature toughness, but the alloy is inferior to TNM alloy in terms of density and service temperature [9] . Recent research prospects suggest that connecting TNM alloy with Ti2AlNb alloy through welding can effectively utilize the advantages of these two materials to prepare large-sized and complex components [10] .…”

The Polythermal Section of Ti-22Al-xNb (30-78at.%Ti) in Ti–Al–Nb System

“…The addition of an appropriate amount of niobium can significantly improve the oxidation resistance, the thermal deformation and hot creep properties of these alloys [3]. Ti 2 AlNb alloys are typical representatives of them [4,5]. The general composition of these alloys is usually Ti-(18-30 at.%) Al-(12.5-30 at.%) Nb.…”

Enhancing the Mechanical Properties of Hot Roll Bonded Al/Ti Laminated Metal Composites (LMCs) by Pre-Rolling Diffusion Process

“…For LMCs, many researches were focused on the fabrication processing, microstructure and mechanical properties [7][8][9]. A number of plastic deformation processes have been applied to the fabrication of LMCs including roll bonding [10,11], diffusion bonding [12][13][14], explosive welding [14,15] and reaction hot pressing [16,17]. Among these methods, roll bonding was widely used in the fabrication of Al/Ti LMCs due to relatively simple equipment and processing.…”