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Schmitz-Niederau, Martin; Schütze, M.

doi:10.1023/a:1018839511102

Cited by 104 publications

(24 citation statements)

References 7 publications

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“…From Fig. 1, in the case of Ti-50Al without TiAl 3 film (bare Ti-50Al), the oxidation curve seems to coincide with the reported studies, 9,15 which has the rapid oxidation rate, severe mass gain and scale spallation after 4 hr of exposure at 1000 • C. This is due to the formation of fragile TiO 2 oxide on the outer surface. Besides, the slopes of 1000 • C isothermal oxidation curves of Ti-50Al alloys with and without TiAl 3 film will be gradually identical when the oxidation time exceeds 20 hr.…”

Section: Isothermal Oxidation Testssupporting

confidence: 82%

“…15 Moreover, an Al-depleted layer forms beneath the oxide scale during 800 • C oxidation. Many recent reports with respect to sub-surface zones indicated that there are two phases in the Al-depleted layer, one is α 2 -Ti 3 Al(O-rich) phase and the other is a new cubic phase (Z-phase) with a very limited composition range of Ti x Al y O z .…”

Section: Introductionmentioning

confidence: 99%

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

Chu

2005

Oxid Met

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Isothermal oxidation tests at 1000 • C in air indicate that the Ti-50Al alloy with about 8 µm TiAl 3 layer on the surface can resist the oxidation for 10 hr. From the FESEM and EPMA/EDS results, the rapid oxidation behavior is attributed to the formation of oxide nodules through the protective Al 2 O 3 and TiAl 2 layers on the outer surface. Upon increasing the oxidation time at 1000 • C, the size and the number of oxide nodules increase. After 3 hr of oxidation at 1000 • C, a laminated layer is formed in between the oxide nodule and substrate, which consists of two nearly parallel phases. The EDS results suggest that these two phases are Ti-Al-O compounds. After 20 hr oxidation, the oxidation nodules and laminated layers disappear and a complex oxide scale is formed which is similar to the bare Ti-50Al oxidized at 1000 • C.

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Section: Isothermal Oxidation Testssupporting

confidence: 82%

Section: Introductionmentioning

confidence: 99%

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

Chu

2005

Oxid Met

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“…Although the maximum scale thickness was 4.15 ± 1.13 lm, the extension of the region of ''hardness-influence'' is attributed to the diffusion of alloying elements in this region. The most influential element is most likely Nb, as shown in Figure 17 and as reported by Schmitz-Niederau and Schu¨tze, [14] where under elevated-temperature air exposure, it had a higher concentration at the subscale than at the bulk material. This could be the reason for the drop in the fracture toughness of the exposed samples.…”

Section: B Elevated-temperature Dynamic Fracture Toughness Of Gamma-supporting

confidence: 67%

“…[12][13][14] The effects of various alloying elements on the oxidation rate have also been studied; Nb appears to be the most influential element, because it provides an effective barrier to the oxidation rate. [15] Other alloying elements such as Si, Cr, and V were also found to improve the oxidation resistance.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Fracture Initiation Toughness of a Gamma (Met-PX) Titanium Aluminide at Elevated Temperatures

Shazly

Prakash

Draper

2009

Metall Mater Trans A

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Recently, a new generation of titanium aluminide alloy named Gamma-Met PX (GKSS, Geesthacht, Germany) has been developed with better rolling and postrolling characteristics. Previous work on this alloy has shown the material to have higher strengths at room and elevated temperatures when compared with other gamma titanium aluminides. In particular, this new alloy has shown increased ductility at elevated temperatures under both quasistatic and high-strain-rate uniaxial compressive loading. However, its high-strain-rate tensile ductility at room and elevated temperatures is limited to~1 pct. In the present article, the results of a study investigating the effects of the loading rate and test temperature on the dynamic fracture initiation toughness in Gamma-Met PX are presented. A modified split Hopkinson pressure bar (MSHPB) was used along with high-speed photography, to determine the dynamic fracture initiation toughness. Three-point-bend fracture tests were conducted at impact speeds in the range 1 to 3.6 m/s and at test temperatures up to 1200°C. Furthermore, the effect of long-time high-temperature air exposure on the fracture toughness was investigated. The results show that the dynamic fracture initiation toughness decreases at test temperatures beyond 600°C. Moreover, the dynamic fracture initiation toughness was found to decrease with increasing exposure time. The reasons behind this drop are analyzed and discussed.

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“…A continuous alumina scale was observed on top of the coating oxidised for 120 cycles. The increase in mass gain of the Ti-Al-Cr coated specimen after 420 cycles was associated with accelerated oxidation probably caused by crack formation in the alumina layer [9] through thermal cycling or related to an Al-depleted area below the oxide scale [29]. Fig.…”

Section: Ti-al-cr Coatingsmentioning

confidence: 92%

Oxidation protective coatings for γ‐TiAl – recent trends

Fröhlich¹,

Ebach-Stahl

Braun

et al. 2007

Materialwissenschaft Werkst

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Engine designers show continued interest in c-TiAl based titanium aluminides as light-weight structural materials to be used at moderately elevated temperatures. Although alloy development has made significant progress in terms of mechanical properties and environmental resistance, protective coatings have been developed that help to extend the lifetime of these alloys significantly. The major challenge of coating development is to prevent the formation of fast growing titania. Furthermore, changes of coating chemistries at high temperatures have to be considered in order to avoid rapid degradation of the coatings due to interdiffusion between substrate and coating.The paper describes recent work of the authors on different coatings produced by means of magnetron sputter technique. Thin ceramic Ti-Al-Cr-Y-N layers tested at 900 C exhibited poor oxidation resistance. In contrast, intermetallic Ti-Al-Cr, Si-based and aluminum rich Ti-Al coatings were tested at exposure temperatures up to 950 C for 1000h resulting in reasonable and partially excellent oxidation behaviour.Keywords Dieser Artikel beschreibt aktuelle Arbeiten der Autoren an unterschiedlichen Schichtsystemen, die mittels Magnetron-Sputtern hergestellt wurden. Dünne keramische Ti-Al-Cr-Y-N -Schichten zeigten einen geringen Oxidationswiderstand bei einer Testtemperatur von 900 C. Dagegen wurden intermetallische Ti-Al-Cr-, Sibasierte und aluminiumreiche Ti-Al -Schichten bis zu 950 C Auslagerungstemperatur 1000h lang getestet mit gutem und teilweise exzellentem Oxidationsverhalten als Ergebnis.

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Cited by 104 publications

References 7 publications

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

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

Dynamic Fracture Initiation Toughness of a Gamma (Met-PX) Titanium Aluminide at Elevated Temperatures

Oxidation protective coatings for γ‐TiAl – recent trends

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