SANS investigation of precipitation hardening of two-phase ?-TiAl alloys

Staron, Peter; Christoph, U.; Appel, F.; Clemens, Helmut

doi:10.1007/s003390201870

Cited by 21 publications

(26 citation statements)

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“…Studies concerning the formation and coarsening of Perovskite-type precipitates in carbon containing TiAl alloys were conducted by means of small angle neutron scattering. [55] In TiAl alloys, the g-phase dissolves at the a-transus temperature. If the specimen is cooled slowly afterwards, the formation of g-lamellae occurs within the supersaturated, disordered a-grains.…”

Section: Formation Of Lamellar Microstructurementioning

confidence: 99%

The Contribution of High‐Energy X‐Rays and Neutrons to Characterization and Development of Intermetallic Titanium Aluminides

et al. 2011

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Intermetallic γ‐TiAl based alloys are a novel class of lightweight structural materials that exhibit excellent high‐temperature strength while having low density. These properties make them ideal candidates for replacing dense Ni base alloys currently used in the temperature range from 550 to 750 °C. Therefore, extensive research activities were conducted during the last 20 years to make this innovative class of materials fit for service. In this task, diffraction methods have been an important tool for promoting the development of TiAl alloys. The ability to perform experiments in situ and to determine phase fractions even in cases where two phases are present in ultrafine lamellar structures are only two examples for applications in which diffraction methods are indispensable. In this work, a review is given concerning the use of diffraction methods in the development of TiAl alloys. Different methods are introduced and highlighted by examples. This review lists the advantages of diffraction experiments and critically discusses the limits of the individual methods.

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Section: Formation Of Lamellar Microstructurementioning

confidence: 99%

The Contribution of High‐Energy X‐Rays and Neutrons to Characterization and Development of Intermetallic Titanium Aluminides

et al. 2011

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“…Small-angle neutron scattering (SANS) studies proved the presence of p-type precipitates in a Ti-48.5Al-0.4C (at. %) alloy after a solution treatment for 4 h at 1250˝C followed by ageing for 24 h at 750˝C and quenching [42]. As a result of the precipitation-hardening treatment, the material's high-temperature strength was improved.…”

Section: Small-angle Scattering Experiments On Carbide Precipitation mentioning

confidence: 95%

“…The recorded diffraction patterns were azimuthally integrated using the software program Fit2D [97]. The derived scattering curves were fit within SANSFit based on a least-squares method iteration, as conducted in [42]. The p-type carbides were modelled as elongated ellipsoids of revolution.…”

Section: Small-angle Scattering Experiments On Carbide Precipitation mentioning

confidence: 99%

“…Carbon and Si are known to act as solid solution strengtheners [40,41]. In addition to this, precipitates (cubic Ti 3 AlC, hexagonal Ti 2 AlC or Ti 5 Si 3 ) tend to form during high-temperature creep experiments [42][43][44]. Detailed knowledge of the associated precipitation processes, however, is still needed for their deliberate application to improve a material's high-temperature properties.…”

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In Situ Characterization Techniques Based on Synchrotron Radiation and Neutrons Applied for the Development of an Engineering Intermetallic Titanium Aluminide Alloy

Erdely

Schmoelzer

Schwaighofer

et al. 2016

Metals

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Abstract:Challenging issues concerning energy efficiency and environmental politics require novel approaches to materials design. A recent example with regard to structural materials is the emergence of lightweight intermetallic TiAl alloys. Their excellent high-temperature mechanical properties, low density and high stiffness constitute a profile perfectly suitable for their application as advanced aero-engine turbine blades or as turbocharger turbine wheels in next-generation automotive engines. As the properties of TiAl alloys during processing as well as during service are dependent on the phases occurring, detailed knowledge of their volume fractions and distribution within the microstructure is of paramount importance. Furthermore, the behavior of the individual phases during hot deformation and subsequent heat treatments is of interest to define reliable and cost-effective industrial production processes. In situ high-energy X-ray diffraction methods allow tracing the evolution of phase fractions over a large temperature range. Neutron diffraction unveils information on order-disorder transformations in TiAl alloys. Small-angle scattering experiments offer insights into the materials' precipitation behavior. This review attempts to shine a light on selected in situ diffraction and scattering techniques and the ways in which they promoted the development of an advanced engineering TiAl alloy.

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“…Data evaluation was performed by means of the program Fit2D with respect to azimuthal integration [1,2] followed by a fitting procedure of the derived scattering curves with the program SANSFit based on a least-square method iteration as conducted in Ref. [3]. More details about the experimental conditions and the obtained results are given in the original full-length paper in [4].…”

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confidence: 99%

In situ small-angle X-ray scattering study of the perovskite-type carbide precipitation behavior in a carbon-containing intermetallic TiAl alloy using synchrotron radiation

Schwaighofer¹,

Staron²,

Rashkova³

et al. 2014

Acta Materialia

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Intermetallic γ-TiAl based alloys of the latest generation, e.g. TNM alloys with a nominal composition of , exhibit the potential to be used in modern high-performance combustion engines due to their low density, high strength and creep-resistance as well as their good oxidation properties at elevated temperatures. Alloying with C can further improve the high-temperature performance both by solid solution hardening and/or carbide formation. In this study, starting from a supersaturated TNM-1C alloy the precipitation behavior and thermal stability of Perovskite-type carbides Ti 3 AlC during isothermal annealing at 750 °C and ensuing re-heating to 1200 °C is quantified by means of an in-situ small-angle X-ray scattering (SAXS) experiment using synchrotron radiation. Complementary, the formed hierarchical structures on the nano-scale, i.e. p-type carbide precipitates within ultra-fine γ-lamellae of the α 2 /γ-colonies, were investigated by means of monochromatic high-energy X-ray diffraction (HEXRD) in combination with transmission electron microscopy (TEM). Additionally, an explanation of an obtained diffraction phenomenon is given, i.e. streak formation which is caused by the very small lamellar spacing of the γ-phase within the α 2 /γ-colonies. It was also found that the geometrically well-defined nanostructure allows a correlation between the γ-laths thickness and a characteristic dimension of p-type carbides.The experiments were carried out at the HZG high-energy materials science beamline HEMS (P07). A sketch of the experimental setup is depicted in Fig. 1. The monochromatic beam with a mean energy of 100 keV is guided through the sample which is situated in a modified quenching and deformation dilatometer device DIL 805 A/D from Bähr Thermoanalyse, Germany. The diffraction patterns are recorded with a Perkin Elmer XRD 1622 flat panel detector in experimental hutch EH 3, whereas a mar345 Image Plate detector located behind in EH 4 is used to record the signal from small-angle scattering. The cylindrical sample with a size of 5 mm in diameter and 10 mm in length was heated inductively. The SAXS data were recorded with a sample-to-detector distance of 11.654 m and a frame rate of 20 images per hour. Slits made of pure tungsten minimized undesired scattering and, thus, ensured a low background. Data evaluation was performed by means of the program Fit2D with respect to azimuthal integration [1,2] followed by a fitting procedure of the derived scattering curves with the program SANSFit based on a least-square method iteration as conducted in Ref. [3]. More details about the experimental conditions and the obtained results are given in the original full-length paper in [4].

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SANS investigation of precipitation hardening of two-phase ?-TiAl alloys

Cited by 21 publications

References 0 publications

The Contribution of High‐Energy X‐Rays and Neutrons to Characterization and Development of Intermetallic Titanium Aluminides

The Contribution of High‐Energy X‐Rays and Neutrons to Characterization and Development of Intermetallic Titanium Aluminides

In Situ Characterization Techniques Based on Synchrotron Radiation and Neutrons Applied for the Development of an Engineering Intermetallic Titanium Aluminide Alloy

In situ small-angle X-ray scattering study of the perovskite-type carbide precipitation behavior in a carbon-containing intermetallic TiAl alloy using synchrotron radiation

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