Development and evaluation of TiAl sheet structures for hypersonic applications

Draper, Susan L.; Krause, David L.; Lerch, Bradley A.; Locci, Ivan E.; Doehnert, B.; Nigam, R.; Das, G.; Sickles, P.; Tabernig, B.; Reger, N.; Rissbacher, Klaus

doi:10.1016/j.msea.2007.02.020

Cited by 65 publications

(22 citation statements)

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“…These applications include airframe hot structures and thermal protection coatings for systems in aerospace vehicles operating under extreme temperature and environmental conditions (Ref [1][2][3][4][5].…”

Section: Introductionmentioning

confidence: 99%

Effects of Al Content and Addition of Third Element on Fabrication of Ti-Al Intermetallic Coatings by Heat Treatment of Warm-Sprayed Precursors

et al. 2015

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Four powder mixtures of titanium and aluminum with 50:50, 40:60, 30:70, and 20:80 atomic ratios were used as feedstock for Warm Spray process to produce composite coatings. A two-stage heat treatment at 600 and 1000°C was applied to the deposits in order to obtain titanium aluminide intermetallic phases. The microstructure, chemical, and phase composition of the as-deposited and heat-treated coatings were investigated using SEM, EDS, and XRD. It was found that the Al content affects on the thickness expansion of the heat-treated Ti-Al coatings significantly and also has a major influence on the porosity development, which is caused by the Kirkendall effect. The effects of adding a third element Si and heat treatment with pressure to produce denser Ti-Al intermetallic coating were also examined. The investigated hot-pressed coatings with addition of Si exhibited much denser microstructure and contained TiAl intermetallic phases with titanium silicide precipitates.

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Section: Introductionmentioning

confidence: 99%

Effects of Al Content and Addition of Third Element on Fabrication of Ti-Al Intermetallic Coatings by Heat Treatment of Warm-Sprayed Precursors

et al. 2015

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“…The alloy shows excellent mechanical properties, with 907-939 MPa yield strength, 917-1033 MPa ultimate tensile strength and 1.08-1.44% of elongation to fracture for rolled sheet material at 23 8C. [6] However, the low ductility and fracture toughness of g-TiAl-based alloys at ambient temperature and their limited weldability restrict their industrial and commercial application. [1] Laser beam and electron beam welding has been tried to produce sound TiAl joint.…”

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confidence: 99%

Investigation of In Situ and Conventional Post‐Weld Heat Treatments on Dual‐Laser‐Beam‐Welded γ‐TiAl‐Based Alloy

et al. 2012

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The g-TiAl materials is an attractive alternative candidate for aerospace and automotive applications because of its properties, such as low density (%3.8 g cm À3 ), high specific yield strength at high temperature, and high creep and oxidation resistance. [1][2][3][4][5] The high niobium containing TNB alloy with the composition of Ti-45Al-5Nb-0.2C-0.2B (at.%) has been developed by the Helmholtz-Zentrum Geesthacht (HZG) for applications in turbine construction. The alloy shows excellent mechanical properties, with 907-939 MPa yield strength, 917-1033 MPa ultimate tensile strength and 1.08-1.44% of elongation to fracture for rolled sheet material at 23 8C. [6] However, the low ductility and fracture toughness of g-TiAl-based alloys at ambient temperature and their limited weldability restrict their industrial and commercial application. [1] Laser beam and electron beam welding has been tried to produce sound TiAl joint. However, longitudinal and transverse cracks were observed in the welding seam. [7][8][9] The material is intrinsically brittle and the high cooling rate results in a welding zone with high residual stress and thermal strain.Nevertheless, it was reported that with proper selection of the cooling rate, butt joining can be achieved for small work pieces. [9] Thus, the goal of the present work is to improve the welding zone microstructure and reduce the residual stress of laser beam-welded specimens via post-weld heat treatments, which is important for increasing the weldable specimen size. Materials and ExperimentsTNB powder material was produced using a powder metallurgical approach by means of gas atomization in the PIGA (plasma melting induction guiding gas atomization) facility at HZG. The powder particles were degassed, welded, hot-isostatically pressed (HIP), and finally extruded into a cylindrical rod. Plates of 13 Â 50 Â 2 mm 3 were extracted by electro-discharge machining (EDM) and subsequently cleaned to remove oxides and remnants. The two laser beams were simultaneously generated by two Nd:YAG laser operation stations (power output P 1 : 0-2200 W, P 2 : 0-3300 W). A robot was used to operate the work station and laser beam movement (Figure 1a). One laser beam for in situ heat treatment was defocused into a large spot size and used for whole-plate (d ¼ 60 mm, see Figure 1b) and local (d ¼ 20-40 mm, see Figure 1b) pre-heating, to ensure the temperature of the welding line was above the brittleductile transition region. The second laser was used for keyhole welding. The plates were positioned in a closed chamber, which was filled with argon to protect the specimen from oxidation. Helium was used as the working gas, and it was injected from the welding cone from above. During butt welding, a minimal clamping force was applied on the work pieces to keep them in place. COMMUNICATION[*] J. This paper describes a way to improve the microstructure and mechanical properties of welding seams by in situ and conventional post-weld heat treatments for laser beam welding of the Ti-45Al-5Nb-0.2C-0.2B allo...

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“…Such as well-known Gamma Met sheet (Ti-46.5Al-4(Cr, Nb, Ta, B)) and GM PX sheets (TM5Al-5Nb-B-C) reported in Ref. [9], and Ti-45.5Al-2Cr-2Nb sheet reported in Ref. [16], nearly no B2 phase can be found in the as-rolled condition.…”

Section: Resultsmentioning

confidence: 77%

“…To overcome these problems, tremendous efforts have been devoted to preparing TiAl alloys with refined and homogeneous microstructures, such as alloying [5], heat treatment [6], thermo-mechanical treatment (TMT) [7][8][9][10], including isothermal forging, pack forging, hot extrusion and rolling etc. Gamma TiAl sheets have extremely promising aerospace applications, including nozzle tiles for gas turbine engines, nozzles for helicopters, back structures for scramjets, and thermal protection systems for reusable launch vehicles (RLV) etc.…”

Section: Introductionmentioning

confidence: 99%

Evolution of Microstructures and Properties of Ti‐44Al‐6V‐3Nb‐0.3Y Alloy after Forging and Rolling

Chen¹,

Niu²,

Xiao³

et al. 2012

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Development and evaluation of TiAl sheet structures for hypersonic applications

Cited by 65 publications

References 1 publication

Effects of Al Content and Addition of Third Element on Fabrication of Ti-Al Intermetallic Coatings by Heat Treatment of Warm-Sprayed Precursors

Effects of Al Content and Addition of Third Element on Fabrication of Ti-Al Intermetallic Coatings by Heat Treatment of Warm-Sprayed Precursors

Investigation of In Situ and Conventional Post‐Weld Heat Treatments on Dual‐Laser‐Beam‐Welded γ‐TiAl‐Based Alloy

Evolution of Microstructures and Properties of Ti‐44Al‐6V‐3Nb‐0.3Y Alloy after Forging and Rolling

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