Selected Methods of Quantitative Phase Analysis of an Additively Manufactured TNM Titanium Aluminide Alloy

Wartbichler, Reinhold; Bürstmayr, Richard; Clemens, Helmut; Mayer, Svea

doi:10.3139/147.110574

Cited by 10 publications

(10 citation statements)

References 13 publications

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“…Figure b shows the phase fraction diagram of the Ti‐42.05Al‐4.11Nb‐1.01Mo alloy as a function of the temperature, which is also in good accordance with the experimental data . The results of the calculation of the equilibrium phase fractions at 1050 and 1100 °C are shown in Table together with the results of quantitative phase analysis based on X‐ray diffraction (XRD) measurements performed in a previous study . These results seem to emphasize that, in fact, the building temperature is slightly above the preheating temperature.…”

Section: Comparison Of the Equilibrium Phase Fractions Based On Calphsupporting

confidence: 85%

“…Subsequent solid state phase transformations occur with respect to the local chemical composition and lead, therefore, to heterogeneous phase distributions. These inhomogeneous phase distributions of an electron‐beam‐melted TNM alloy have also been reported in a previous study, and aggravate successful quantitative phase analyses.…”

Section: Comparison Of the Equilibrium Phase Fractions Based On Calphsupporting

confidence: 57%

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Electron Beam Melting of a β‐Solidifying Intermetallic Titanium Aluminide Alloy

2019

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The structural features of an electron‐beam‐melted titanium aluminide alloy are presented. The microstructure consisting of γ‐TiAl, α2‐Ti3Al, and βo‐TiAl reveals inhomogeneous phase and Al distributions, which are quantified by electron probe microanalysis. Electron backscatter diffraction is utilized to indicate a solidification via the β‐phase preferably along the <001> direction, resulting in a {001}βo fiber texture parallel to the building direction. These findings are correlated to a calculated isopleth section of the Ti‐Al‐Nb‐Mo system and the corresponding phase fraction diagram. The investigated β‐solidifying γ‐TiAl‐based alloy, therefore, combines both the characteristics of electron‐beam‐melted Ti and TiAl alloys.

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Section: Comparison Of the Equilibrium Phase Fractions Based On Calphsupporting

confidence: 85%

Section: Comparison Of the Equilibrium Phase Fractions Based On Calphsupporting

confidence: 57%

Electron Beam Melting of a β‐Solidifying Intermetallic Titanium Aluminide Alloy

2019

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“…The relatively new fabrication route of additive manufacturing (AM) has not attained full industrial readiness yet, but recent results in this field, especially those connected with the process of electron beam melting (EBM), are considered encouraging. [86][87][88][89][90][91][92] AM, i.e., the layer-by-layer build-up of parts, offers special advantages compared with the other conventional manufacturing routes. These include an improved material yield, a reduction in postprocessing operations, and a high degree of product customization, as it allows the production of parts with complicated geometries (e.g., internal cavities, channels, lattice structures, and bioinspired geometries) and integrated functional features.…”

Section: Common Manufacturing Routes and Heat Treatmentsmentioning

confidence: 99%

“…In the EBM process, a focused electron beam is used to selectively melt TiAl powder layers. [86][87][88][89][90][91][92]94,96,97] Due to the highvacuum environment, the process is particularly attractive for the fabrication of γ-TiAl-based parts, because they are highly susceptible to impurity uptake of O, N, and C. [98] Furthermore, the optics of the electron beam offer the possibility to keep the chamber temperature on elevated levels during AM, allowing for the fabrication of highly dense parts with comparably small residual stresses. [93] In contrast to this, γ-TiAl-based parts fabricated by means of selective laser melting (SLM) frequently suffer from both potential impurity uptake and higher residual stresses, as [22] ).…”

Section: Common Manufacturing Routes and Heat Treatmentsmentioning

confidence: 99%

Exploring Structural Changes, Manufacturing, Joining, and Repair of Intermetallic γ‐TiAl‐Based Alloys: Recent Progress Enabled by In Situ Synchrotron X‐Ray Techniques

et al. 2021

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Intermetallic titanium aluminides based on the ordered γ-TiAl phase fulfil many of the key requirements of lightweight high-temperature applications. In addition to a high melting point, high specific Young's modulus and strength at elevated temperatures, excellent creep properties, and a satisfactory oxidation and burn resistance, especially their low density of roughly 4 g cm À3 makes them a material of choice for challenging structural applications such as found, e.g., in environmentally friendly combustion engine options. [1][2][3][4] Capable of withstanding extreme conditions, γ-TiAl-based alloys have already entered service as low-pressure turbine blades in jet engines, such as the GEnx engine by GE Aviation, [5] the Geared Turbofan (GTF) engine by Pratt and Whitney, [6] as well as the LEAP engine by CFM International, a joint company between Safran Aircraft Engines and GE. [7,8] In these applications, γ-TiAl-based turbine blades substitute some of the blades made of twice as heavy Ni-base superalloys in a temperature range up to 750 °C. The implementation of the advanced, lightweight material, which is also attended by an adaptation of the design, entails a substantial reduction in weight, fuel consumption, and CO 2 and NO x emissions. [9] Apart from the aircraft engine industry, γ-TiAl-based alloys have also found applications in the automotive industry, e.g., as engine valves in sports and racing cars or as turbocharger turbine wheels. [1,3,[10][11][12][13][14] The past few decades have witnessed great efforts to develop intermetallic γ-TiAl-based alloy systems that are suitable for service in these demanding areas while being economically competitive at the same time. To this end, various alloy compositions and processing routes have been studied intensively. [1,[15][16][17][18][19][20][21] Recent progress has been reviewed, e.g., in the works by Appel et al., Clemens et al., and Mayer et al. [1,3,9,22] Due to the complexity of the intermetallic alloy system, which encompasses a multitude of phases and phase transformations, [23] purposeful alloy design requires the use of manifold characterization methods. Diffraction and scattering techniques, in particular, offer access to the atomic structure of the material and provide insights into a variety of microstructural parameters. [24][25][26][27] High-energy X-rays, such as available at today's synchrotron radiation sources, and recent developments in hardware technology nowadays allow to conduct so-called in situ experiments. Experiments of this kind reveal-at a high temporal resolution-the relationship between selected external

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“…[ 3,9,19,21 ] Mechanical properties of TiAl parts remain highly microstructure‐sensitive, [ 8 ] which makes clarifying the processing‐microstructure–property relationship a necessity. Several different additively manufactured TiAl alloys were already investigated, such as the aforementioned Ti–(47–48)Al–2Cr–2Nb alloy, [ 3,21–42 ] or the TNM alloy, [ 43–45 ] as well as high Nb bearing TiAl alloys. [ 46–52 ] Many different microstructures of these various electron beams melted titanium aluminide alloys were reported, generally fine‐grained.…”

Section: Introductionmentioning

confidence: 99%

On the Formation Mechanism of Banded Microstructures in Electron Beam Melted Ti–48Al–2Cr–2Nb and the Design of Heat Treatments as Remedial Action

et al. 2021

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The formation mechanism of banded microstructures of an electron beam melted engineering intermetallic Ti–48Al–2Cr–2Nb alloy, the solidification behavior, and the heat treatment response are investigated via a process parameter study. Scanning electron microscopy, hardness testing, X‐ray diffraction, electron probe microanalysis, thermomechanical analysis, electron backscatter diffraction, heat treatments, as well as thermodynamic equilibrium calculation, and numerical simulation were performed. All specimens show near‐γ microstructures with low amounts of α2 and traces of βo. Fabrication with an increased energy input leads to an increased Al loss due to evaporation, a lower α‐transus temperature, and to a higher hardness. Banded microstructures form due to abnormal grain growth toward the bottom of original melt pools, whereas α2 in Al‐depleted zones enables a Zener pinning of the γ‐grain boundaries, leading to fine‐grained areas. Via numerical simulation, it is shown that increasing the energy input leads to larger maximum temperatures and melt pool sizes, longer times in the liquid state, and more remelting events. Solidification happens via the α‐phase and increasing the energy input leads to an alignment of (111)γ in building direction. Furthermore, banded microstructures respond heterogeneously to heat treatments. Heat treatment is introduced based on homogenization via phase transformation to obtain isotropic microstructures.

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Selected Methods of Quantitative Phase Analysis of an Additively Manufactured TNM Titanium Aluminide Alloy

Cited by 10 publications

References 13 publications

Electron Beam Melting of a β‐Solidifying Intermetallic Titanium Aluminide Alloy

Electron Beam Melting of a β‐Solidifying Intermetallic Titanium Aluminide Alloy

Exploring Structural Changes, Manufacturing, Joining, and Repair of Intermetallic γ‐TiAl‐Based Alloys: Recent Progress Enabled by In Situ Synchrotron X‐Ray Techniques

On the Formation Mechanism of Banded Microstructures in Electron Beam Melted Ti–48Al–2Cr–2Nb and the Design of Heat Treatments as Remedial Action

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