Investigation into the microstructure and mechanical properties of diffusion bonded TiAl alloys

Çam, Gürel; İpekoğlu, Güven; Bohm, Karl Heinz; Koçak, M.

doi:10.1007/s10853-006-0292-4

Cited by 52 publications

(15 citation statements)

References 20 publications

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“…This is in agreement with the results of others [13,14,16]. In diffusion bonded TiAl alloys, the bond interface was clearly visible due to the discontinuity of the grains in both sides of each join, and the α 2 phase formed in the bond interface because of oxygen and nitrogen contamination of the contact surface [10]. During friction welding when the hot interface material contacts the atmosphere at the initial friction step, oxygen and nitrogen contamination cannot be completely avoided [22].…”

Section: Resultssupporting

confidence: 92%

“…This can change the composition and properties of the alloys. In the diffusion welding process, oxygen and nitrogen contamination of the mating surfaces cannot be avoided [10]. Rotary friction welding (RFW) is one of the best processing techniques for joining these axisymmetric TiAl parts [11], because neither the filler material nor any inert gas is needed to ensure the welding joint is uncontaminated with the same composition as the parent metal (PM) [12].…”

Section: Introductionmentioning

confidence: 99%

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Friction Weldability of a High Nb Containing TiAl Alloy

Lin

Guo

2019

Materials

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The friction weldability of Ti-45Al-8.5Nb-0.2W-0.2B-0.02Y alloy has been investigated by optimizing process parameters and analyzing the microstructures and tensile properties of the joints. The as-cast alloy with a nearly lamellar (NL) microstructure and the as-forged alloys with a duplex (DP) microstructure have been successfully welded. All the joints have a severe deformation zone (SDZ) and a transition zone (TZ) between the parent metal (PM) and SDZ. SDZ, showing a biconcave lens geometry, has a maximum thickness of hundreds of micrometers at the periphery. TZ is hundreds of micrometers thick. All SDZs have a fine-grained DP microstructure with a grain size of a few micrometers. For the joint of the as-cast alloy, the TZ consists of deformed lamellar colonies as the major constituent and partially recrystallized grains as the minor constituent. For the joint of the as-forged alloy, the TZ is similar to both the PM and SDZ, showing a DP microstructure. The grain size, volume fraction of γ grains, and the remnant lamellar colonies all increase with the distance from the SDZ. All joints presented perfect metallurgical bonding. The strengths of the joints are higher than those of the corresponding PMs. This indicates that the studied alloy has good friction weldability.

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Section: Resultssupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Friction Weldability of a High Nb Containing TiAl Alloy

Lin

Guo

2019

Materials

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“…Several techniques for joining TiAl are reported in the literature (see, for instance, Froes et al, 1992; Threadgill, 1995; Lee et al, 1997). Nevertheless, diffusion bonding is the most promising technique for bonding these alloys, as it avoids stress cracking, the main problem with fusion-welding processes (Çam et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

TEM and HRTEM Characterization of TiAl Diffusion Bonds Using Ni/Al Nanolayers

et al. 2014

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Diffusion bonding of TiAl alloys can be enhanced by the use of reactive nanolayer thin films as interlayers. Using these interlayers, it is possible to reduce the conventional bonding conditions (temperature, time, and pressure) and obtain sound and reliable joints. The microstructural characterization of the diffusion bond interfaces is a fundamental step toward understanding and identifying the bonding mechanisms and relating them to the strength of the joints. The interface of TiAl samples joined using Ni/Al nanolayers was characterized by transmission electron microscopy and scanning transmission electron microscopy. Microstructural characterization of the bond revealed that the interfaces consist of several thin layers of different composition and grain size (nanometric and micrometric). The bonding temperature (800, 900, or 1,000°C) determines the grain size and thickness of the layers present at the interface. Phase identification by high-resolution transmission electron microscopy combined with fast Fourier transform and electron energy-loss spectroscopy analyses reveals the presence of several intermetallic compounds: AlTiNi, NiAl, and Al2TiNi. For bonds produced at 800 and 900°C, nanometric grains of Ti were detected at the center of the interface.

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“…During their work on the Ti-45Al-2Nb-2Mn + 0.8 vol.% TiB 2 alloy, Chaturvedi et al [12] recommend that the α-γ phase transformation not be suppressed during EBW, suggesting that the critical cooling rate at the fusion zone boundary is 250 K s −1 . Solid-state joining techniques such as diffusion bonding (DB), have been utilised where TiAl alloys have been bonded to themselves [17,18]; other alloys [19], and utilising interlayers [20,21] without the concern of solid-state cracking. However, the formation of the brittle α 2 phase along the bond line during DB can degrade mechanical properties due to the development of favourable crack paths [18].…”

Section: Introductionmentioning

confidence: 99%

“…Solid-state joining techniques such as diffusion bonding (DB), have been utilised where TiAl alloys have been bonded to themselves [17,18]; other alloys [19], and utilising interlayers [20,21] without the concern of solid-state cracking. However, the formation of the brittle α 2 phase along the bond line during DB can degrade mechanical properties due to the development of favourable crack paths [18]. Diffusion brazing [22], diffusion welding [23] and induction brazing [24,25] have all been used to join TiAl alloys without solid-state cracking.…”

Section: Introductionmentioning

confidence: 99%

The joining of gamma titanium aluminides via the powder interlayer bonding method

Davies

Watkins

et al. 2020

Int J Adv Manuf Technol

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Powder interlayer bonding (PIB) is a joining technique originally developed to enable high-integrity repairs of aerospace components. The technique has previously been employed for the joining of titanium and nickel alloys utilised in the aerospace industry. This study expands on the application of the novel joining technique known as powder interlayer bonding (PIB), to the bonding of γ titanium aluminide (TiAl) material. PIB has been used to facilitate high-integrity joints in gamma titanium aluminides (TiAl), where full densification of the joint was achieved. The PIB technique described here used a metallic powder interlayer between the two faying surfaces of γ TiAl specimens. Bonds were formed in an inert atmosphere under induction heating. The PIB technique proved capable of producing high-integrity bonds in terms of microstructural evaluation, with very limited porosity retained after the bonding cycle. A brittle Ti 2 Al phase can be produced with heavily oxidised powder which is susceptible to cracking and will negatively affect mechanical properties.

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Investigation into the microstructure and mechanical properties of diffusion bonded TiAl alloys

Cited by 52 publications

References 20 publications

Friction Weldability of a High Nb Containing TiAl Alloy

Friction Weldability of a High Nb Containing TiAl Alloy

TEM and HRTEM Characterization of TiAl Diffusion Bonds Using Ni/Al Nanolayers

The joining of gamma titanium aluminides via the powder interlayer bonding method

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