Microstructure Characteristics after combustion and fireproof mechanism of TiAl-based alloys

Ouyang, Peixuan; Cao, Jingxia; Xu, Huibin; He, Ling; Li, Peijie

doi:10.1016/j.mtcomm.2018.07.012

Cited by 18 publications

(6 citation statements)

References 18 publications

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“…Then, the alloy releases a tremendous amount of heat, and the titanium alloy begins to combust when the temperature reaches the ignition point. According to the literature [26], the combustion flame temperature of the titanium alloy is approximately 2700 °C, which is much higher than its melting point, so the titanium alloy will be melted. As is well known, the dissolved oxygen in the melting alloy is higher than that in the solid alloy, and the combustion reaction is very violent until all the sample is burned away.…”

Section: Resultsmentioning

confidence: 99%

Combustion Mechanism of Alloying Elements Cr in Ti-Cr-V Alloys

et al. 2019

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The combustion velocity and the mechanism for a series of Ti-Cr-V alloys with different chemical compositions are studied by a promoted ignition combustion test corresponding to different oxygen pressures to investigate the influence of alloying elements, such as Cr and V, on combustion behavior. The microstructures and composition distributions of the alloying elements in the reaction and oxide areas are observed and analyzed. The thermogravimetry analysis results show that the oxidation mass gain decreases with the increasing Cr content, and the oxidation resistance obviously increases from 10 Cr to 20 Cr. The combustion velocity decreases with increasing Cr content, and it is concluded that elevated Cr content can effectively retard the flame propagation velocity. Importantly, for the Ti-Cr-V alloys, the Cr and V elements accumulate in the melting zone and reduce the heat created by combustion.

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Section: Resultsmentioning

confidence: 99%

Combustion Mechanism of Alloying Elements Cr in Ti-Cr-V Alloys

et al. 2019

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“…However, at the same time of the oxide growth, the sintering reaction between TiO 2 and Al 2 O 3 in the oxide scale (mainly in the TiO 2 + Al 2 O 3 mixed layer) aggravated and an β-Al 2 TiO 5 -rich layer was formed in the oxide scale (Figure 14a). Since Al 2 TiO 5 has higher oxygen resistance than TiO 2 [5,43], the formation of the β-Al 2 TiO 5 -rich layer could effectively slow down the inward diffusion of oxygen and the oxidation rate decreased. Hence, the decelerated oxidation behavior of the Ti-46Al-2Cr-5Nb alloy at Stage V is due to the generation of an oxygen-barrier β-Al 2 TiO 5 -rich layer in the oxide scale by the reaction between TiO 2 and Al 2 O 3 in large scales.…”

Section: Resultsmentioning

confidence: 99%

“…TiAl-based alloys have received considerable attention as high-temperature structural materials for aerospace and automotive applications, since they maintain numerous outstanding properties, such as low density (3.9–4.2 g/cm 3 ), high specific strength, good creep resistance and excellent fireproof performance [1,2,3,4,5]. Nevertheless, the insufficient high-temperature oxidation resistance of the TiAl-based alloys limits their wide application and development [6,7].…”

Section: Introductionmentioning

confidence: 99%

Non-Isothermal Oxidation Behaviors and Mechanisms of Ti-Al Intermetallic Compounds

Ouyang

et al. 2019

Materials

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Non-isothermal oxidation is one of the important issues for the safe application of Ti-Al alloys, so this study aimed to illustrate the non-isothermal oxidation behaviors and the corresponding mechanisms of a TiAl-based alloy in comparison with a Ti3Al-based alloy. The non-isothermal oxidation behaviors of Ti-46Al-2Cr-5Nb and Ti-24Al-15Nb-1.5Mo alloys in pure oxygen were comparatively investigated with a thermogravimetry-differential scanning calorimetry (TGA/DSC) simultaneous thermal analyzer heating from room temperature to 1450 °C with a heating rate of 40 °C/min. When the temperature rose above 1280 °C, the oxidation rate of the Ti-46Al-2Cr-5Nb alloy sharply increased and exceeded that of the Ti-24Al-15Nb-1.5Mo alloy owing to the occurrence of internal oxidation. When the temperature was higher than 1350 °C, the oxidation rate of the Ti-46Al-2Cr-5Nb alloy decreased obviously due to the generation of an oxygen-barrier β-Al2TiO5-rich layer by a chemical reaction between Al2O3 and TiO2 in the oxide scale. Based on Wagner’s theory of internal oxidation, the reason for the occurrence of internal oxidation in the Ti-46Al-2Cr-5Nb alloy is the formation of the α phase in the subsurface, while no internal oxidation occurred in the Ti-24Al-15Nb-1.5Mo alloy due to the existence of the β phase in the subsurface with the enrichment of Nb and Mo.

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“…For instance, γ-TiAl alloys play an essential role in the development of aero-engines with a high thrust-weight ratio. These alloys have superior characteristics, including low density, high specific strength, significant creep resistance, and corrosion resistance in working temperatures of 500 ~ 850 ℃ [1][2][3][4]. However, further investigations showed that γ-TiAl alloys suffer from a potential safety hazard called "titanium fire" during the service at high temperatures.…”

Section: Introductionmentioning

confidence: 99%

Preparation of NiCr/YSZ two-layered burn-resistant coating on γ-TiAl alloys based on plasma surface metallurgy and ion plating methods

Wei

Zhou

et al. 2021

J min metall B Metall

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The NiCr/YSZ coating was fabricated on ?-TiAl alloy by double glow plasma surface metallurgy technology and multi-arc ion plating technology. The microstructure, microhardness, bonding strength and burn resistance of NiCr/YSZ coating were studied in detail. The results showed that the NiCr/YSZ coating was dense and homogeneous, including a duplex structure of top YSZ ceramic coating and underlying Ni-Cr bond coating. The average microhardness of NiCr/YSZ coating was raised by a factor of about 2 compared to the ?-TiAl substrate. The thermal shock test indicated that the composite structure had superior bonding strength and the defects such as metal droplets on the ceramic coating were the source of cracks. The high-energy laser beam destroyed the surface of ?-TiAl alloy, forming protruding combustion products in ablation zone and splashing residues around ablation zone. When coated by NiCr/YSZ coating, the combustion process was delayed through isolating and dissipating heat. The ablation range was controlled and the ablation damage was reduced at the same irradiation power. The NiCr/YSZ coating preliminarily realized to improve the burn resistance of ?-TiAl alloy.

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Microstructure Characteristics after combustion and fireproof mechanism of TiAl-based alloys

Cited by 18 publications

References 18 publications

Combustion Mechanism of Alloying Elements Cr in Ti-Cr-V Alloys

Combustion Mechanism of Alloying Elements Cr in Ti-Cr-V Alloys

Non-Isothermal Oxidation Behaviors and Mechanisms of Ti-Al Intermetallic Compounds

Preparation of NiCr/YSZ two-layered burn-resistant coating on γ-TiAl alloys based on plasma surface metallurgy and ion plating methods

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