Preparation of TiAl3 Coating on γ-TiAl through Hot-dip Aluminizing and Subsequent Interdiffusion Treatment

Zhang, Z.G.; Teng, Xinying; Xiang, Hong Fu; Sheng, Yu; Zhang, X.J.

doi:10.1515/htmp.2009.28.1-2.115

Cited by 7 publications

(5 citation statements)

References 19 publications

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“…Other methods of diffusive aluminising of TiAl alloys are also being developed, including out of pack [7] and chemical vapour deposition (CVD) [8]. It is also possible to apply an aluminide coating to the substrate using one of the following methods: cold spray [9], Arc-PVD [10], galvanic [11], slurry [12], hot-dip [13], followed by diffusion annealing. Thermal barrier coatings (TBC) are produced to increase heat resistance on TiAl alloys with, among others, bond coats [14].…”

Section: Introductionmentioning

confidence: 99%

Thermal Barrier Coating Deposited Using the PS-PVD Method on TiAl-Nb-Mo Intermetallic Alloy with Different Types of Bond Coats

Góral

Kubaszek

Kobylarz

et al. 2021

SSP

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TiAl intermetallics can be considered an alternative for conventional nickel superalloys in the high-temperature application. A TBC (Thermal Barrier Coatings) with ceramic topcoat with columnar structure obtained using EB-PVD (electron beam physical vapour deposition) is currently used to protect TiAl intermetallics. This article presents the new concept and technology of TBC for TiAl intermetallic alloys. Bond coats produced using the slurry method were obtained. Si and Al nanopowders (70 nm) were used for water-based slurry preparation with different composition of solid fraction: 100 wt.% of Al, 50 wt.% Al + 50 wt.% Si and pure Si. Samples of TNM-B1 (TiAl-Nb-Mo) TiAl intermetallic alloy were used as a base material. The samples were immersed in slurries and dried. The samples were heat treated in Ar atmosphere at 1000 °C for 4 h. The outer ceramic layer was produced using the new plasma spray physical vapour deposition (PS-PVD) method. The approximately 110 μm thick outer ceramic layers contained yttria-stabilised zirconium oxide. It was characterised by a columnar structure. Differences in phase composition and structures were observed in bond coats. The coatings obtained from Al-contained slurry were approximately 30 μm thick and consisted of two zones: the outer contained the TiAl3 phase and the inner zone consisted of the TiAl2 phase. The second bond coat produced from 50 wt.% Al + 50 wt.% Si slurry was characterised by a similar thickness and contained the TiAl2 phase, as well as titanium silicides. The bond coat formed from pure-Si slurry had a thickness < 10 μm and contained up to 20 at % of Si. This suggests the formation of different types of titanium silicides and Ti-Al phases. The obtained results showed that PS-PVD method can be considered as an alternative to the EB-PVD method, which is currently applied for deposition a columnar structure ceramic layer. On the other hand, the use of nanopowder for slurry production is problematic due to the smaller thickness of the produced coating in comparison with conventional micro-sized slurries.

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Section: Introductionmentioning

confidence: 99%

Thermal Barrier Coating Deposited Using the PS-PVD Method on TiAl-Nb-Mo Intermetallic Alloy with Different Types of Bond Coats

Góral

Kubaszek

Kobylarz

et al. 2021

SSP

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“…Furthermore, the interface between the alloy and the coating is not flat but undulating, and a continuous TiAl3 layer with a mean thickness of 7.3 µm formed at the interface (see Figure 1b). The content of TiAl3 in this Al coating could be controlled by varying the hot-dip aluminizing process [35,36]. Figure 2 shows the schematic illustration of the FSSW-B setup.…”

Section: Introductionmentioning

confidence: 99%

Friction Stir Spot Welding-Brazing of Al and Hot-Dip Aluminized Ti Alloy with Zn Interlayer

Zhou

Chen

et al. 2018

Metals

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Friction stir spot welding (FSSW) of Al to Ti alloys has broad applications in the aerospace and automobile industries, while its narrow joining area limits the improvement of mechanical properties of the joint. In the current study, an Al-coating was prepared on Ti6Al4V alloy by hot-dipping prior to joining, then a Zn interlayer was used during friction stir joining of as-coated Ti alloy to the 2014-Al alloy in a lap configuration to introduce a brazing zone out of the stir zone to increase the joining area. The microstructure of the joint was investigated, and the joint strength was compared with the traditional FSSW joint to confirm the advantages of this new process. Because of the increase of the joining area, the maximum fracture load of such joint is 110% higher than that of the traditional FSSW joint under the same welding parameters. The fracture load of these joints depends on the joining width, including the width of solid-state bonding region in stir zone and brazing region out of stir zone.optimize the mechanical properties of the joint [17][18][19][20][21]. Unavoidably, the traditional FSSW would leave a keyhole that reduces its bonding area [22]. Although some modified processes for FSSW, such as refill FSSW [23], flat FSSW [24], and short travel FSSW [25], have attempted to eliminate this visible keyhole, they are complicated and time-consuming owing to the rigorous welding conditions and/or complex tool design. Recently, friction stir brazing (FSSB) has been developed by using a pinless tool and adding brazing filler metal to induce metallurgical reaction at the interface with the aid of friction heat and forging pressure, instead of plastic flow [22]. This technique has successfully introduced a brazing zone in dissimilar joints of steel/Al [26], Cu/Al [27], and Al /Mg [28], while FSSB of Al and Ti alloys is yet to be reported.This work aims to find an effective approach to improve the joining area of the Al/Ti joint by combining FSSW and FSSB. Zinc (Zn) is an optional filler for FSSB of Al alloys as a result of its low melting point (420 • C), high solubility in Al, as well as absence of formation of IMCs in the Al-Zn alloying system [29][30][31][32]. During our preliminary study, a Zn interlayer was placed between the interface of 2014 Al and Ti6Al4V alloys for the FSSB process to determine their weldability. It was found that the high affinity of Ti towards oxygen led to the formation of non-protective oxide scales on the Ti6Al4V [33], resulting in poor wettability of Zn to Ti alloys and, therefore, failure to join Al and Ti alloys. Recently, using an electroplating process before the FSB process would produce a copper layer on the surface of graphite, which converted the graphite-copper lap joint to the similar joining of copper to copper [34]. This gives us an idea that pretreating the base metal will be a possible benefit for FSSB of Al and Ti.In the present paper, we utilized hot dip to aluminize T6Al4V alloys and developed a friction stir spot joining process, called friction stir spot w...

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“…[6][7][8][9][10][11][12][13][14][15][16] Aluminising has been used for heat-resistant materials as a coating technique that generates an oxidation-resistant aluminide by reaction diffusion. Studies on aluminising TiAl-based alloys have been conducted using various techniques such as pack cementation, [17][18][19] hot-dip coating, [20][21][22] gas phase aluminising 23 and annealing of electrically plated substrates. 24 The purpose of these aluminising processes is essentially to form an Al-rich intermetallic layer of TiAl 3 , which has a higher oxidation resistance.…”

Section: Introductionmentioning

confidence: 99%

Two-step diffusion treatment of aluminium-coated TiAl-based alloy

Sasaki

Yagi

2016

Surface Engineering

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Aluminising of thermal sprayed TiAl-based alloys (49.1 at-% Al) was conducted by a two-step diffusion treatment at 7008C and 11008C. The coating morphology is strongly dependent on the diffusion temperature; a poreless and thicker TiAl 3 layer is obtained at a temperature of 7008C, while the intermediate layer predominantly grows at a temperature of 11008C. In addition, the second diffusion treatment at 11008C can also decrease the overall pore volume in the TiAl 3 layer. In a cyclic oxidation test at 9008C in the air, TiO 2 scale predominantly grows in pores and cracks that occur in the coating, and this promotes the oxidation. It is demonstrated that the two-step diffusion treatment improves the oxidation resistance of aluminide coating on TiAl-based alloys because of the formation of poreless TiAl 3 and the crack suppression by the intermediate layer.

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Preparation of TiAl3 Coating on γ-TiAl through Hot-dip Aluminizing and Subsequent Interdiffusion Treatment

Cited by 7 publications

References 19 publications

Thermal Barrier Coating Deposited Using the PS-PVD Method on TiAl-Nb-Mo Intermetallic Alloy with Different Types of Bond Coats

Thermal Barrier Coating Deposited Using the PS-PVD Method on TiAl-Nb-Mo Intermetallic Alloy with Different Types of Bond Coats

Friction Stir Spot Welding-Brazing of Al and Hot-Dip Aluminized Ti Alloy with Zn Interlayer

Two-step diffusion treatment of aluminium-coated TiAl-based alloy

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