Orientation relationship of eutectoid FeAl and FeAl<sub>2</sub>

Scherf, Anke; Kauffmann, Alexander; Kauffmann-Weiss, Sandra; Scherer, Torsten; Li, Xin; Stein, Frank; Heilmaier, Martin

doi:10.1107/s1600576716000911

Cited by 15 publications

(10 citation statements)

References 14 publications

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“…In contrast to expectations in Ref. [20] there is no evidence for preferential orientation of the high temperature phase with respect to the solidification direction even though a rather large range of withdrawal rates was tested, namely 6 to 240 mm/h. Nevertheless, columnar Fe5Al8 grains form at high withdrawal rates which results in columnar eutectoid colonies after completion of the eutectoid reaction.…”

Section: The Fe-al Systemcontrasting

confidence: 93%

A zone melting device for the in situ observation of directional solidification using high-energy synchrotron x rays

Gombola

Hasemann

Kauffmann

et al. 2020

Review of Scientific Instruments

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Directional solidification (DS) is an established manufacturing process to produce highperformance components from metallic materials with optimized properties. Materials for demanding high-temperature applications, for instance in energy generation and aircraft engine technology, can only be successfully produced using methods such as directional solidification.It has been applied on an industrial scale for a considerable amount of time, but advancing this method beyond the current applications is still challenging and almost exclusively limited to post-process characterization of the developed microstructures. For a knowledge-based advancement and a contribution to material innovation, in-situ studies of the DS process are crucial using realistic sample sizes to ensure scalability of the results to industrial sizes. Therefore, a specially designed Flexible Directional Solidification (FlexiDS) device was developed for use at the P07 High Energy Materials Science (HEMS) beamline at PETRA III (Deutsches Elektronen-Synchrotron (DESY); Hamburg, Germany). In general, the process conditions of the crucible-free, inductively heated FlexiDS device can be varied from 6 to 12000 mm/h (vertical withdrawal rate) and from 0 to 35 rpm (axial sample rotation).Moreover, different atmospheres like Ar, N2, vacuum can be used during operation. The device is designed for maximum operation temperatures of 2200 °C. This unique device allows in-situ examination of the directional solidification process and subsequent solid-state reactions by Xray diffraction in the transmission mode. Within this project, different structural intermetallic alloys with liquidus temperatures up to 2000 °C were studied in terms of liquid-solid regions, transformations and decompositions, with varying process conditions.

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Section: The Fe-al Systemcontrasting

confidence: 93%

A zone melting device for the in situ observation of directional solidification using high-energy synchrotron x rays

Gombola

Hasemann

Kauffmann

et al. 2020

Review of Scientific Instruments

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“…The FeAl phase has a B2 structure, while the FeAl 2 phase has a triclinic structure ( Fig. 1D ) ( 33 – 35 ). Figure 1E provides a closer view of the layered FeAl/FeAl 2 region as a bright-field TEM image.…”

Section: Resultsmentioning

confidence: 99%

Achieving room-temperature brittle-to-ductile transition in ultrafine layered Fe-Al alloys

Beyerlein

et al. 2020

Sci. Adv.

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Fe-Al compounds are of interest due to their combination of light weight, high strength, and wear and corrosion resistance, but new forms that are also ductile are needed for their widespread use. The challenge in developing Fe-Al compositions that are both lightweight and ductile lies in the intrinsic tradeoff between Al concentration and brittle-to-ductile transition temperature. Here, we show that a room-temperature, ductile-like response can be attained in a FeAl/FeAl2 layered composite. Transmission electron microscopy, nanomechanical testing, and ab initio calculations find a critical layer thickness on the order of 1 μm, below which the FeAl2 layer homogeneously codeforms with the FeAl layer. The FeAl2 layer undergoes a fundamental change from multimodal, contained slip to unimodal slip that is aligned and fully transmitting across the FeAl/FeAl2 interface. Lightweight Fe-Al alloys with room-temperature, ductile-like responses can inspire new applications in reactor systems and other structural applications for extreme environments.

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“…After a directional solidification process, NiAl‐Cr(Mo) develops a cellular structure with NiAl and Cr(Mo) lamellae parallel to the growth direction . Similar microstructures are observed for other intermetallics, for example, titanium‐aluminides or iron‐aluminides . To investigate mechanical behavior of a lamellar NiAl‐Cr(Mo) alloy, a cellular microstructure with 512 grains was generated using the Voronoi tessellation routine of the software Neper .…”

Section: Numerical Demonstrationsmentioning

confidence: 87%

“…69 Similar microstructures are observed for other intermetallics, for example, titanium-aluminides 70 or iron-aluminides. 71,72 To investigate mechanical behavior of a lamellar NiAl-Cr(Mo) alloy, a cellular microstructure with 512 grains was generated using the Voronoi tessellation routine of the software Neper. 73 Based on findings by Whittenberger et al 74 and Raj and Locci 75 for moderate solidification rates, an aspect ratio of 4 along the growth direction parallel to the y-axis was chosen for the grains.…”

Section: Directionally Solidified Nial-cr(mo) Alloymentioning

confidence: 99%

On Quasi‐Newton methods in fast Fourier transform‐based micromechanics

Wicht

Schneider

Böhlke

2019

Numerical Meth Engineering

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SUMMARY This work is devoted to investigating the computational power of Quasi‐Newton methods in the context of fast Fourier transform (FFT)‐based computational micromechanics. We revisit FFT‐based Newton‐Krylov solvers as well as modern Quasi‐Newton approaches such as the recently introduced Anderson accelerated basic scheme. In this context, we propose two algorithms based on the Broyden‐Fletcher‐Goldfarb‐Shanno (BFGS) method, one of the most powerful Quasi‐Newton schemes. To be specific, we use the BFGS update formula to approximate the global Hessian or, alternatively, the local material tangent stiffness. Both for Newton and Quasi‐Newton methods, a globalization technique is necessary to ensure global convergence. Specific to the FFT‐based context, we promote a Dong‐type line search, avoiding function evaluations altogether. Furthermore, we investigate the influence of the forcing term, that is, the accuracy for solving the linear system, on the overall performance of inexact (Quasi‐)Newton methods. This work concludes with numerical experiments, comparing the convergence characteristics and runtime of the proposed techniques for complex microstructures with nonlinear material behavior and finite as well as infinite material contrast.

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Orientation relationship of eutectoid FeAl and FeAl₂

Abstract: The orientation relationship and interface plane of eutectoid FeAl and FeAl2 lamellae are investigated in detail and a crystallographic model is proposed.

Cited by 15 publications

References 14 publications

A zone melting device for the in situ observation of directional solidification using high-energy synchrotron x rays

A zone melting device for the in situ observation of directional solidification using high-energy synchrotron x rays

Achieving room-temperature brittle-to-ductile transition in ultrafine layered Fe-Al alloys

On Quasi‐Newton methods in fast Fourier transform‐based micromechanics

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Orientation relationship of eutectoid FeAl and FeAl2

Abstract: The orientation relationship and interface plane of eutectoid FeAl and FeAl2 lamellae are investigated in detail and a crystallographic model is proposed.

Cited by 15 publications

References 14 publications

A zone melting device for the in situ observation of directional solidification using high-energy synchrotron x rays

A zone melting device for the in situ observation of directional solidification using high-energy synchrotron x rays

Achieving room-temperature brittle-to-ductile transition in ultrafine layered Fe-Al alloys

On Quasi‐Newton methods in fast Fourier transform‐based micromechanics

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Orientation relationship of eutectoid FeAl and FeAl₂