Synthesis and characterization of lamellar and fibre-reinforced NiAl-Mo and NiAl-Cr

Haenschke, T.; Gali, Aravind; Heilmaier, Martin; Krüger, Manja; Bei, Hongbin; George, E.P.

doi:10.1088/1742-6596/240/1/012063

Cited by 13 publications

(5 citation statements)

References 10 publications

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“…The resulting microstructure is composed of NiAl as matrix and an embedded second phase, which causes a reinforcement [1,[8][9][10][11]. With this goal in mind, several directionally solidified NiAl-X alloys have been studied in the past, namely NiAl-10Mo (in what follows all concentrations are given in at.% unless otherwise stated) [1][2][3][4]8,[10][11][12][13],…”

Section: Introductionmentioning

confidence: 99%

Microstructural Investigations of Novel High Temperature Alloys Based on NiAl-(Cr,Mo)

Gombola

Kauffmann

Geramifard

et al. 2020

Metals

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Apart from the reported transition from the fibrous morphology in NiAl-34Cr to lamellae by adding 0.6 at.% Mo, further morphology transformations along the eutectic trough in the NiAl-(Cr,Mo) alloys were observed. Compositions with at least 10.3 at.% Cr have lamellar morphology while the first tendency to fiber formation was found at 9.6 at.% Cr. There is a compositional range, where both lamellae and fibers are present in the microstructure and a further decrease in Cr to 1.8at.% Cr results in fully fibrous morphology. Alongside these morphology changes of the (Cr,Mo)ss reinforcing phase, its volume fraction was found to be from 41 to 11 vol.% confirming the trend predicted by the CALPHAD approach. For mixed morphologies in-situ X-ray diffraction experiments performed between room and liquidus temperature accompanied by EDX measurements reveal the formation of a gradient in composition for the solid solution. A new Mo-rich NiAl-9.6Cr-10.3Mo alloy clearly shows this effect in the as-cast state. Moreover, crystallographic orientation examination yields two different types of colonies in this composition. In the first colony type, the orientation relationship between NiAl matrix and (Cr,Mo)ss reinforcing phase was ( 100 ) NiAl|| ( 100 ) Cr,Mo and ⟨ 100 ⟩ NiAl|| ⟨ 100 ⟩ Cr,Mo. An orientation relationship described by a rotation of almost 60° about ⟨ 111 ⟩ was found in the second colony type. In both cases, no distinct crystallographic plane as phase boundary was observed.

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Section: Introductionmentioning

confidence: 99%

Microstructural Investigations of Novel High Temperature Alloys Based on NiAl-(Cr,Mo)

Gombola

Kauffmann

Geramifard

et al. 2020

Metals

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“…Moreover, the here chosen systems reveal a better creep resistance compared to NiAl-V [22]. Due to this, several experimental studies of the directionally solidified ternary alloys NiAl-Mo [23][24][25][26][27][28] and NiAl-Cr [28][29][30][31] have been conducted in the past.…”

Section: The Quaternary System Nial-(crmo)mentioning

confidence: 97%

Phase-Field Simulation of the Microstructure Evolution in the Eutectic Alloy NiAl-31Cr-3Mo

et al. 2023

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The directionally solidified eutectic alloy NiAl-(Cr,Mo) is a promising candidate for structural applications at high temperatures, due to its increased creep resistance compared to its single phase B2ordered NiAl counterpart. This system yields an eutectic trough connecting the invariant reactions of the ternary alloys NiAl-Cr and NiAl-Mo. During directional solidification (DS) along this trough the evolved microstructures of the two-phase eutectic is changing from fibrous to lamellar and back to fibrous morphology while increasing and decreasing the amounts of Mo and Cr, respectively. To investigate these effects in the morphology, the phase-field method has proven to be predestined in the last decades. However, as the modeling of quaternary systems is challenging for the simulation with a grand potential based phase-field model, the focus of this work is on the generation of a material model for one defined compound namely NiAl-31Cr-3Mo. The modeling is validated by investigating the microstructure evolution in two- and three-dimensional simulations of the DS process for two different growth velocities and by investigating their undercooling spacing relationships. The evolving microstructures obtained from three-dimensional large-scale simulations are presented and validated with corresponding micrographs from scanning electron microscopy (SEM) of directionally solidified samples with the same growth velocities. The simulation results show the theoretically expected behaviors and are in qualitative and quantitative accordance with DS experiments. The study of NiAl-31Cr-3Mo serves as the basis for a comprehensive data-driven analysis of microstructure properties and system quantities of the entire quaternary material NiAl-(Cr,Mo). With this, an accelerated design of advanced materials is promoted.

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“…The considered microstructure with 84 unidirectionally aligned fibers with square cross‐section was generated using the random sequential addition algorithm 96 and resolved by 1200 × 160 × 160 voxels. The fibers have an aspect ratio of 100 105 and take up 14 % of the overall volume. Following Albiez et al, 106 the behavior of fibers and matrix is governed by a single‐crystal elastoviscoplasticity model based on Hooke's law

σ = ℂ : (ε - ε_{p}), with ε = ε_{e} + ε_{p}

and the classical power‐law flow rule by Hutchinson 107

{\dot{ε}}_{p} = \sum_{α = 1}^{N} {\dot{γ}}_{α} d_{α} \otimes^{s} n_{α} with {\dot{γ}}_{α} = {\dot{γ}}_{0} sgn (τ_{α}) {|\frac{τ_{α}}{τ^{F}}|}^{m},

where

d_{α}

and

n_{α}

denote the slip direction and the slip‐plane normal, respectively,

{\dot{γ}}_{0}

is the reference slip‐rate and

τ^{F}

is the yield stress.…”

Section: Numerical Demonstrationsmentioning

confidence: 99%

Anderson‐accelerated polarization schemes for fast Fourier transform‐based computational homogenization

Wicht

Schneider

Böhlke

2021

Numerical Meth Engineering

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Classical solution methods in fast Fourier transform‐based computational micromechanics operate on, either, compatible strain fields or equilibrated stress fields. By contrast, polarization schemes are primal‐dual methods whose iterates are neither compatible nor equilibrated. Recently, it was demonstrated that polarization schemes may outperform the classical methods. Unfortunately, their computational power critically depends on a judicious choice of numerical parameters. In this work, we investigate the extension of polarization methods by Anderson acceleration and demonstrate that this combination leads to robust and fast general‐purpose solvers for computational micromechanics. We discuss the (theoretically) optimum parameter choice for polarization methods, describe how Anderson acceleration fits into the picture, and exhibit the characteristics of the newly designed methods for problems of industrial scale and interest.

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Synthesis and characterization of lamellar and fibre-reinforced NiAl-Mo and NiAl-Cr

Cited by 13 publications

References 10 publications

Microstructural Investigations of Novel High Temperature Alloys Based on NiAl-(Cr,Mo)

Microstructural Investigations of Novel High Temperature Alloys Based on NiAl-(Cr,Mo)

Phase-Field Simulation of the Microstructure Evolution in the Eutectic Alloy NiAl-31Cr-3Mo

Anderson‐accelerated polarization schemes for fast Fourier transform‐based computational homogenization

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