A method of heat-treatment of near γ-TiAl to enhance oxidation resistance by the formation of a Ti5Si3 layer

Gray, Simon; Jacobs, Michael; Ponton, C. B.; Voice, W.; Evans, Hugh E.

doi:10.1016/s0921-5093(04)00868-8

Cited by 13 publications

(6 citation statements)

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“…Ti 62.5 Si 37.5 , Ti 55. 6 Si 44.4 , Ti 50 Si 50 and Ti 33.3 Si 66.7 powder blends according to the Ti 5 Si 3 , Ti 5 Si 4 , TiSi and TiSi 2 stoichiometries, respectively, were ball-milled under 6 bars of high-purity helium gas (H 2 O < 3 ppm, O 2 < 2 ppm and CnHm < 0.5 ppm, Air Liquide) using a modified planetary ball-mill (model Micro Mill Pulverisette 7, Fritsch). Five grams of powder, together with seven tempered steel balls, were placed in a tempered steel vial (67 Rc) for each milling experiment.…”

Section: Methodsmentioning

confidence: 99%

“…For the milled Ti 55. 6 Si 44.4 mixture, the high-temperature Ti 5 Si 4 structure disappeared after the thermal treatment and only Ti 5 Si 3 and TiSi phases were observed (Fig. 3b).…”

Section: Thermal Nitriding Of Mechanically Alloyed Ti/si Mixturesmentioning

confidence: 98%

“…For the other two mixtures, Ti 55 6. Si 44.4 , and Ti 50 Si 50 , a combination of several intermetallic phases was found.…”

mentioning

confidence: 91%

“…For this reason, intermetallic matrix composites reinforced with ceramic materials (carbides, nitrides, and oxides) are receiving increasing attention [3,4]. Much research is currently focused on the development of titanium silicide protective coatings on structural materials, in order to improve the oxidation resistance of these materials [5,6]. In a recent work [7], it has been shown in Ti 5 Si 3 that nitrogen was responsible for the increased oxidation in air above 1000 C, which can limit some of its high-temperature applications.…”

Section: Introductionmentioning

confidence: 99%

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Nitriding study of titanium silicide intermetallics obtained by mechanical alloying

et al. 2008

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Section: Methodsmentioning

confidence: 99%

“…For the milled Ti 55. 6 Si 44.4 mixture, the high-temperature Ti 5 Si 4 structure disappeared after the thermal treatment and only Ti 5 Si 3 and TiSi phases were observed (Fig. 3b).…”

Section: Thermal Nitriding Of Mechanically Alloyed Ti/si Mixturesmentioning

confidence: 98%

“…For the other two mixtures, Ti 55 6. Si 44.4 , and Ti 50 Si 50 , a combination of several intermetallic phases was found.…”

mentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

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Nitriding study of titanium silicide intermetallics obtained by mechanical alloying

et al. 2008

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“…The resistance to oxidation of TiAl alloys was also increased by the method of liquid phase siliconization with Al–Si alloy [ 28 ]. Silicon surface treatments are described, for example, in articles [ 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 ]. Siliconizing is a treatment to improve the chemical and mechanical properties of intermetallics based on TiAl system.…”

Section: Properties Of Tial Alloys and Effect Of Silicon On Themmentioning

confidence: 99%

Development of TiAl–Si Alloys—A Review

et al. 2021

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This paper describes the effect of silicon on the manufacturing process, structure, phase composition, and selected properties of titanium aluminide alloys. The experimental generation of TiAl–Si alloys is composed of titanium aluminide (TiAl, Ti3Al or TiAl3) matrix reinforced by hard and heat-resistant titanium silicides (especially Ti5Si3). The alloys are characterized by wear resistance comparable with tool steels, high hardness, and very good resistance to oxidation at high temperatures (up to 1000 °C), but also low room-temperature ductility, as is typical also for other intermetallic materials. These alloys had been successfully prepared by the means of powder metallurgical routes and melting metallurgy methods.

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Improvement of the High‐Temperature Oxidation Resistance of γ‐TiAl by Selectively Pre‐treated Si‐based Coating

et al. 2008

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Light weight materials are interesting for high temperature applications in the aerospace as well as automotive industries. Especially for highly stressed components, where materials with low density are requested, c-TiAl based alloys are attractive to replace the heavy steels and nickel-based alloys because of their good mechanical properties including high specific stiffness, high tensile strength and good creep resistance in a temperature range from 700°C up to 900°C. [1][2][3] Titanium aluminides based on c-TiAl were tested successfully as parts of automotive engines [2,3] as well as components in aeroengines, [4] such as low pressure turbine blades. However, application of titanium aluminides is limited to service temperatures below about 750°C due to insufficient oxidation resistance at higher temperatures caused by the formation of fast growing and porous titania. [5][6][7][8][9] To improve the oxidation behaviour of TiAl the formation of non protective TiO 2 has to be prevented. A method to increase the oxidation resistance of c-TiAl is the use of coatings. [10,11] As reported in the literature, Si-based coatings can form stable titanium silicide phases with good oxidation resistance. [12][13][14][15][16][17] In this work Ti-Si coatings were deposited on c-TiAl based material, and their protection capability was evaluated. ExperimentalThe material used was c-TiAl based Ti-45Al-8Nb alloy (in at%), provided by GfE, Germany. From extruded rods discshaped specimens with 15 mm diameter and 1 mm thickness were machined; their surfaces were ground using SiC paper up to 4000 grit, polished and cleaned. On the samples a 10 lm thick Si-25 at% Ti coating was deposited by magnetron sputtering using a dual source equipment [18,19] with an elemental silicon target on a RF-source and an elemental titanium target on a DC-source.After coating deposition the samples were annealed under high-vacuum conditions (10 -6 mbar) at 1000°C for 100 h in order to form surface layers of stable titanium silicides by interdiffusion. Besides high-vacuum annealing, some of the coated specimens were pre-oxidised in air at 750°C for 100 h.The oxidation resistance of the pre-treated coated specimens was studied performing mass gain measurements during thermal cycling at 900°C in air. One cycle consisted of 1h heating and 10 min cooling down to 60°C. To study the evolution of microstructure and phase formation during exposure the samples were examined after different exposure time periods (10, 100 and 1000 cycles) using scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) spectroscopy. Results and DiscussionCross-sections of coated samples which were high-vacuum annealed or pre-oxidised in air are shown in Figures 1 and 2. No oxidation was observed during the annealing process at 1000°C. Owing to interdiffusion between substrate and Si-25Ti-coating a 13 lm thick titanium silicide layer formed, consisting of a broad Ti 5 Si 3 layer and a thinner outer Ti 5 Si 4 film (Fig. 1). In comparison to high-vacuum annealed samples, the p...

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A method of heat-treatment of near γ-TiAl to enhance oxidation resistance by the formation of a Ti5Si3 layer

Cited by 13 publications

References 0 publications

Nitriding study of titanium silicide intermetallics obtained by mechanical alloying

Nitriding study of titanium silicide intermetallics obtained by mechanical alloying

Development of TiAl–Si Alloys—A Review

Improvement of the High‐Temperature Oxidation Resistance of γ‐TiAl by Selectively Pre‐treated Si‐based Coating

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