Oxidation Behavior of Ti--50Al Intermetallics with Thin TiAl3 Film at 1000�C

Chu, M. S.; Wu, S.K.

doi:10.1007/s11085-005-1948-1

Cited by 21 publications

(14 citation statements)

References 22 publications

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“…The internal oxidation of Al during oxidation of TiAl 3 coating was seldom reported in Refs. [12,21,35]. Another problem is that the internal oxidation of Al in the coating occurred at different temperature because of the difference between the two oxidation modes, i.e.…”

Section: Improvement Of the High Temperature Oxidation Resistancementioning

confidence: 99%

“…Different diffusion barrier coatings have been developed. The processes for developing Al-rich coatings on c-TiAl based alloys include pre-oxidation [11], pack cementation [12][13][14][15][16], magnetron sputtering [16][17][18][19][20][21], low-pressure plasma spray [22], and electroplating [23]. In the most of these Al-rich coatings, the TiAl 3 intermetallic is the most important constituent because it is capable of Al 2 O 3 formation at high temperatures due to its high Al content.…”

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confidence: 99%

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Improvement of Oxidation Resistance of γ-TiAl at 900 and 1000 °C Through Hot-dip Aluminizing

et al. 2009

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Hot-dip aluminizing method and subsequent interdiffusion treatment were used to develop a TiAl 3 coating on Ti-45Al-2Cr-2Nb-0.15B (at.%) alloy. A two-phase coating consisting of an outer pure Al layer and an inner TiAl 3 layer formed on the alloy after the hot-dip and then a single phase TiAl 3 coating was obtained by using interdiffusion treatment. Oxidation of the TiAl 3 coating was conducted at 900 and 1000°C. Both the interrupt oxidation and the isothermal oxidation tests indicated that the coating provided high protectiveness for the alloy. The coating was stable for at least 300 h during the interrupt oxidation at 900 and 1000°C, and it was stable for at least 500 h at 1000°C and 1000 h at 900°C during the isothermal oxidation. The oxidation behavior of the coating was discussed in detail.

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Section: Improvement Of the High Temperature Oxidation Resistancementioning

confidence: 99%

mentioning

confidence: 99%

Improvement of Oxidation Resistance of γ-TiAl at 900 and 1000 °C Through Hot-dip Aluminizing

et al. 2009

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“…Besides the pack cementation process magnetron sputtering techniques were used to produce aluminide coatings on c-TiAl [26][27][28][29]. On Ti-50Al (at.%) specimens coated with 5 lm thick aluminium films, which were annealed at 650°C in vacuum, a TiAl 3 layer formed exhibiting good adhesion to the substrate [27].…”

Section: Introductionmentioning

confidence: 99%

Oxidation Behaviour of TBC Systems on γ-TiAl Based Alloy Ti–45Al–8Nb

et al. 2009

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The lifetime of thermal barrier coating (TBC) systems on gamma titanium aluminides was determined in the temperature range between 850°C and 950°C under cyclic oxidation conditions in air. Coupons of the alloy Ti-45Al-8Nb (at.%) were coated by pack aluminizing. A subset of samples was subsequently annealed at 910°C for 312 h in argon. During this heat treatment, the two-phase (Nb,Ti)Al 3 plus TiAl 2 microstructure of the coating transformed into single phase c-TiAl. On pre-oxidised aluminized, annealed and bare samples, TBCs of yttria partially stabilized zirconia were deposited using electron-beam physical vapour deposition (EB-PVD). No spallation of the TBCs was observed in cyclic oxidation tests at 850°C for up to 3,000 cycles of 1 h dwell time at high temperature. The two-phase aluminide coating provided effective oxidation protection due to the formation of a continuous alumina scale. The lifetime of this TBC system exceeded 1,400 cycles at 950°C, whereas an aluminized and annealed sample failed after approximately 500 cycles. The TBC on bare substrate failed when thermally cycled at 900°C. In contrast, no spallation occurred with an aluminized and annealed specimen at this temperature during the maximum exposure length of 1,000 cycles, probably related to an increased aluminium concentration in the subsurface region.EB-PVD zirconia top coats were well adherent to the alumina scale and the thermally grown mixed oxides. Failure of the TBC systems observed with bare and annealed samples was associated with spalled oxide scales formed on c-TiAl.

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“…However, the low hardness, poor wear resistance, and insufficient oxidation resistance at high temperature of titanium and its alloys limit their wider application [2]. Attempts have been made to remedy these problems, either by incorporating different elements into the alloy [3] or by protecting it through appropriate surface treatments [4]. For example, Shida and Pérez showed that addition of Nb, W, or Mo into TiAl intermetallics increased their resistance to high-temperature oxidation [5][6].…”

Section: Introductionmentioning

confidence: 99%

“…Aluminide diffusion coating [7] is widely used, which can evidently improve the oxidation resistance of titanium substrate. The deposition of a TiAl 3 [4], TiAlCr [8], or stable Al 2 O 3 [9] layer directly to the alloy is also an efficient way to improve the resistance to high-temperature corrosion. TiN and (Ti,Al)N superhard coatings [10] exhibit good wear resistance at high temperature.…”

Section: Introductionmentioning

confidence: 99%

Comparison of molybdenizing and NiCrAlY coating on Ti and Ti-6Al-4V

et al. 2009

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Two surface treatments, molybdenizing and depositing NiCrAlY coating, were applied to improve the microhardness and the oxidation resistance of titanium and Ti-6Al-4V. Coupons were analyzed using optical microscopy (OM), scanning electron microscopy (SEM) with X-ray energy dispersive spectrometer (EDS), and X-ray diffraction (XRD). Vickers hardness and isothermal oxidation tests were carried out to evaluate the effects of these two surface treatments on the microhardness and oxidation resistance of the substrates. The post vacuum heat treatment of the NiCrAlY coating and the molybdenizing parameters were also discussed. It is found that molybdenizing can obviously increase the surface hardness of titanium due to the formation of β, α″, and α′ phases in the diffusion layer. As γ′ phase is formed after vacuum heat treatment, the NiCrAlY coating is effective in improving the surface hardness of Ti-6Al-4V. The NiCrAlY coating can obviously decrease the oxidation rate of Ti-6Al-4V at 700-900°C, which can be attributed to the formation of Al 2 O 3 and Cr 2 O 3 mixed scale during the oxidation.

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Oxidation Behavior of Ti--50Al Intermetallics with Thin TiAl3 Film at 1000�C

Cited by 21 publications

References 22 publications

Improvement of Oxidation Resistance of γ-TiAl at 900 and 1000 °C Through Hot-dip Aluminizing

Improvement of Oxidation Resistance of γ-TiAl at 900 and 1000 °C Through Hot-dip Aluminizing

Oxidation Behaviour of TBC Systems on γ-TiAl Based Alloy Ti–45Al–8Nb

Comparison of molybdenizing and NiCrAlY coating on Ti and Ti-6Al-4V

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