Influence of interface microstructure on the strength of the transition joint between Ti-6Al-4V and stainless steel

Abstract

Solid-state diffusion bonding of Ti-6Al-4V and type 304 SS was investigated in the temperature range of 750 °C to 950 °C, under a uniaxial load for 5.4 ks in vacuum. The diffusion bonds were characterized using light and scanning electron microscopy. The scanning electron microscopic images in backscattered mode show the existence of different reaction layers in the diffusion zone. The composition of these layers was determined by energy-dispersive X-ray spectroscopy (EDS) to contain the ␣-Fe, , , FeTi, ␤-Ti, and Fe 2 Ti 4 O phases. The presence of these intermetallics was confirmed by X-ray diffraction. The bond strength was evaluated, and the maximum tensile strength of ϳ342 MPa and the maximum shear strength of ϳ237 MPa were obtained for the diffusion couple processed at 800 °C due to the finer width of the brittle intermetallic layers. With a rise in joining temperature, the bond strength drops owing to an increase in the width of the reaction layers. The activation energy and growth constant were calculated in the temperature range of 750 °C to 950 °C for the reaction products. The phase showed the fastest growth rate. A fracture-surface observation in a scanning electron microscope (SEM) using EDS demonstrates that failure takes place mainly through the ␤-Ti phase for the diffusion couples processed in the aforementioned temperature range.

Aging Characteristics of Sn-Ag Eutectic Solder Alloy with the Addition of Cu, In, and Mn

“…The linear relationship between the reaction layer thickness and time -½ suggests that the growth is a diffusion-controlled process. Taking the overall thickness of the reaction product into consideration, the relationship can be expressed by [11,22] …”

Numerical simulation and experimental investigation of laser overlap welding of Ti6Al4V and 42CrMo

“…It could be seen through the microhardness testing that the gray and white intermetallic reaction layer had high hardness. Ghosh et al (2005) found that the intermetallic compounds had an essential influence on the mechanical properties of the joint. Thickness of intermetallic reaction layer of the joint was measured and is shown in Table 5.…”

Effects of Intermetallic Phases on the Bond Strength of Diffusion-Bonded Joints between Titanium and 304 Stainless Steel Using Nickel Interlayer

“…Nickel is a strong b-stabilizing element, so migration of Ni atoms in the Ti lattice lowers the eutectoid transformation temperature of Ti and the acicular a-b Ti occurs from b-Ti owing to its decomposition during cooling. [12,19] The deep shaded diffusion area has been observed in the Ni side of both interfaces at 900°C and 950°C bonding temperatures. The width of the diffusion zone at the SS-Ni interface is smaller than that of the diffusion zone at the Ni-Ti interface.…”

“…[7][8][9] Literature reports that, at room temperature, Ti and Fe have limited solubility and promote intermetallic phases. [6,[10][11][12] Characterization of a diffusion couple of Ti-SS using transmission electron microscope study revealed the formation of reaction products such as r, v, Fe 2 Ti, FeTi, Cr 2 Ti, Fe 2 Ti 4 O, and TiC in the diffusion zone. [13] The diffusion bonding temperature has a strong influence on the formation of intermetallic phases.…”