Influence of process parameter variation during thermo-mechanical processing of an intermetallic β-stabilized γ-TiAl based alloy

Huber, Daniel; Werner, Robert; Clemens, Helmut; Stockinger, Martin

doi:10.1016/j.matchar.2015.09.021

Cited by 29 publications

(13 citation statements)

References 12 publications

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“…In the present study, we investigate the influence of pressure on the formation of the ductile β-phase in γ-based TiAl alloys, which is not only of fundamental interest, but is also most relevant to modelling high-pressure deformation techniques, such as high-pressure torsion, in order to achieve severe plastic deformation [11][12][13][14][15] and high-pressure near-net-shape forging [16][17][18][19]. These deformation processes operate at pressures up to 7 GPa and forces exceeding 1 GN, respectively.…”

Section: Introductionmentioning

confidence: 99%

Hydrostatic Compression Behavior and High-Pressure Stabilized β-Phase in γ-Based Titanium Aluminide Intermetallics

Liss

Funakoshi

Dippenaar

et al. 2016

Metals

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Titanium aluminides find application in modern light-weight, high-temperature turbines, such as aircraft engines, but suffer from poor plasticity during manufacturing and processing. Huge forging presses enable materials processing in the 10-GPa range, and hence, it is necessary to investigate the phase diagrams of candidate materials under these extreme conditions. Here, we report on an in situ synchrotron X-ray diffraction study in a large-volume press of a modern (α 2 + γ) two-phase material, Ti-45Al-7.5Nb-0.25C, under pressures up to 9.6 GPa and temperatures up to 1686 K. At room temperature, the volume response to pressure is accommodated by the transformation γ → α 2 , rather than volumetric strain, expressed by the apparently high bulk moduli of both constituent phases. Crystallographic aspects, specifically lattice strain and atomic order, are discussed in detail. It is interesting to note that this transformation takes place despite an increase in atomic volume, which is due to the high ordering energy of γ. Upon heating under high pressure, both the eutectoid and γ-solvus transition temperatures are elevated, and a third, cubic β-phase is stabilized above 1350 K. Earlier research has shown that this β-phase is very ductile during plastic deformation, essential in near-conventional forging processes. Here, we were able to identify an ideal processing window for near-conventional forging, while the presence of the detrimental β-phase is not present under operating conditions. Novel processing routes can be defined from these findings.

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Section: Introductionmentioning

confidence: 99%

Hydrostatic Compression Behavior and High-Pressure Stabilized β-Phase in γ-Based Titanium Aluminide Intermetallics

Liss

Funakoshi

Dippenaar

et al. 2016

Metals

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“…[4][5][6][7]10,11,17,18] The majority of these alloys provide excellent mechanical properties, but frequently exhibit a narrow processing window, with the result that forging under isothermal conditions is favored. [28,35,195,197] In this context also, a recently developed hot-processing route for automotive turbocharger turbine wheels should be mentioned. [28,35,195] For this reason, TNM alloys were developed, which are suited for hot-die forging under near conventional conditions [27,28] and isothermal forging.…”

Section: Manufacturing and Processing Of Advanced Titanium Aluminidesmentioning

confidence: 99%

Intermetallic β‐Solidifying γ‐TiAl Based Alloys − From Fundamental Research to Application

et al. 2017

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Intermetallic titanium aluminides based on the ordered g-TiAl phase have gained increasing interest as innovative high-temperature light-weight structural materials. They have found application in aerospace and automotive industries and are still subject of worldwide research and development activities. Their attractive properties perfectly match the engine manufacturers' demands. This review, bridges the gap from the development of the TNM alloy through structural characterization with sophisticated in and ex situ methods, engineering properties, manufacturing, and processing technologies to all aspects of application. Because one thing is clear, the material still has great potential.

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“…These heat treatments typically comprise three steps [131]. In the first heat treatment step, the material is homogenized as reported in [129].…”

Section: Studies Enabling the Targeted Optimization Of Heat Treatmentmentioning

confidence: 99%

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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Influence of process parameter variation during thermo-mechanical processing of an intermetallic β-stabilized γ-TiAl based alloy

Cited by 29 publications

References 12 publications

Hydrostatic Compression Behavior and High-Pressure Stabilized β-Phase in γ-Based Titanium Aluminide Intermetallics

Hydrostatic Compression Behavior and High-Pressure Stabilized β-Phase in γ-Based Titanium Aluminide Intermetallics

Intermetallic β‐Solidifying γ‐TiAl Based Alloys − From Fundamental Research to Application

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

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