Effects of the stacking fault energy fluctuations on the strengthening of alloys

Zeng, Yifei; Cai, Xiushan; Koslowski, Marisol

doi:10.1016/j.actamat.2018.09.066

Cited by 64 publications

(21 citation statements)

References 41 publications

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“…Further, we find that this material is nearly isotropic, such that assuming elastic isotropy in the calculation is reasonable. Yet MPEAs, in general, may not be assumed as elastic isotropic, as in previous mesoscale modeling work [17,18].…”

Section: Discussionmentioning

confidence: 99%

Ab initio-informed phase-field modeling of dislocation core structures in equal-molar CoNiRu multi-principal element alloys

Beyerlein

2019

Modelling Simul. Mater. Sci. Eng.

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In this work, selecting the equal-molar CoNiRu multi-principal element alloy (MPEA) as a model material, we study dislocation core structures starting from first principles. We begin by sifting through all possible configurations to find those corresponding to elastic stability and energetically favored facecentered cubic (fcc) phases and, then, for these configurations, employ a phase field-based model to predict the extent of dislocations lying within them. The main findings are that for the fcc phase, (i) large variations in atomic configuration for the same chemical composition can cause significant changes in the generalized stacking fault energy surface and (ii) the dispersion in defect fault energies are chiefly responsible for substantial variations in the intrinsic stacking fault (ISF) widths of screw and edge dislocations. For instance, positive the ISF energy can vary by 10 times, with the lower values correlated with entirely Ni and Ru atoms and higher values with only Co and Ru atoms across the slip plane. Variations in lattice parameter and stiffness tensor accompany local differences in atomic configuration are also taken into account but shown to play a lesser role. We find that the dislocation can experience profound variations (3-7-fold changes) in its associated ISF width along its line, with the screw dislocation experiencing a greater variation than the edge dislocation (6.02-43.22 Å for the screw dislocation, and 19.6-62.62 Å for the edge dislocation). We envision that the ab initio-informed phase-field modeling method developed here can be readily adapted to MPEAs with other chemical compositions.

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Section: Discussionmentioning

confidence: 99%

Ab initio-informed phase-field modeling of dislocation core structures in equal-molar CoNiRu multi-principal element alloys

Beyerlein

2019

Modelling Simul. Mater. Sci. Eng.

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“…In particular, this multi-scale approach will allow to relax some assumptions of average models [2,32,33] that rely on a unique dislocation length-scale to predict the critical resolved shear stress of the alloy. Some efforts have been pursued in this direction by investigating dislocation roughening in a random stress environment [35] or the strengthening associated to stacking fault inhomogeneities [54]. However, the stress environment considered in these studies was simplified and did not incorporate stress correlations evidenced in this study.…”

Section: Stress Correlations and Dislocationsmentioning

confidence: 99%

Microelasticity model of random alloys. Part II: displacement and stress correlations

Geslin

Rida

Rodney

2021

Journal of the Mechanics and Physics of Solids

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In this two-part article, we propose elastic models of disordered alloys to study the statistical properties of the random displacement and stress fields emerging from the random distributions of atoms of different sizes. In Part I, we presented realand Fourier-space approaches enabling to obtain the amplitude of the fluctuations through the mean square displacements and stresses. In the present Part II, we extend the Fourier approach to address spatial correlations. We show that, even if the alloy is fully disordered and elastically isotropic, correlations are highly anisotropic. Our continuum predictions are validated by comparisons with atomistic models of random alloys. We also discuss the consequence of displacement correlations on finite size effects in atomistic calculations and on diffuse X-ray and neutron scattering experiments and the possible implications of stress correlations on dislocation behavior.Random alloys are solid solutions of two or more components where atoms of different nature are located randomly on the crystalline lattice. The plasticity of random alloys has been of significant interest for several decades [1, 2, 3] but has recently attracted a renewed attention with the development of high entropy alloys (HEA) [4,5,6]. The size difference between the alloy components induces displacements of the atoms from their lattice sites, as well as internal stresses. These atomic displacements, also referred to as "lattice distortion" in the literature [5,6] have been the focus of multiple studies because they were found to correlate well with solid solution strengthening and can be assessed by both experimental (using X-ray [5

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“…It has been shown that tailoring the atomic ratios of individual components would reduce the SFE value and in turn the phase stability of HEAs at room temperature [15]. In this respect, metastable high entropy alloys (MSHEAs) have been designed [16] which benefit from assistant strengthening mechanisms like twinning induced plasticity (TWIP) or transformation induced plasticity (TRIP) effect in addition to the unique strengthening mechanisms in HEAs, such as stacking fault energy fluctuation, lattice distortion, and local concentration fluctuation [17][18][19][20]. For instance, Deng et al [21] have designed a non-equiatomic single-phase MSHEA with a nominal composition of Fe40Mn40Co10Cr10 in which the TWIP effect leads to enhancement of room temperature mechanical properties in comparison with the wellknown CoCrMnFeNi alloy.…”

Section: Introductionmentioning

confidence: 99%

The high temperature mechanical properties and the correlated microstructure/ texture evolutions of a TWIP high entropy alloy

Nabizada

Zarei-Hanzaki

Abedi

et al. 2021

Materials Science and Engineering: A

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Effects of the stacking fault energy fluctuations on the strengthening of alloys

Cited by 64 publications

References 41 publications

Ab initio-informed phase-field modeling of dislocation core structures in equal-molar CoNiRu multi-principal element alloys

Ab initio-informed phase-field modeling of dislocation core structures in equal-molar CoNiRu multi-principal element alloys

Microelasticity model of random alloys. Part II: displacement and stress correlations

The high temperature mechanical properties and the correlated microstructure/ texture evolutions of a TWIP high entropy alloy

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