Hierarchical microstructure design to tune the mechanical behavior of an interstitial TRIP-TWIP high-entropy alloy

Su, Jing; Raabe, Dierk; Li, Zhi Ming

doi:10.1016/j.actamat.2018.10.017

Cited by 350 publications

(70 citation statements)

References 49 publications

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“…An early study estimated the σ A of 179 MPa [12]. The σ GB can be described by the Hall-Petch relationship, σ GB = k y d −1/2 , where k y is the GB strengthening coefficient, 573 MPa×m m 1/2 [12].…”

Section: Resultsmentioning

confidence: 99%

“…Also, it maintains a high uniform elongation ( u ) of ∼ 28%. Thus, the as-built iHEA possesses a comparable strength-ductility synergy to that of high-performance iHEAs achieved through special hierarchical microstructure design [12]. Figure 2(b) presents the true stress-strain curves superimposed with the corresponding work-hardening rate versus true strain of the as-built iHEA.…”

Section: Methodsmentioning

confidence: 96%

“…Of these strategies, introducing the small-sized atoms, such as carbon, boron and oxygen, to develop the interstitial solute strengthened HEAs (iHEAs) is attractive to manipulate the mechanical properties [4][5][6]. For instance, a carbon-doped iHEA, Fe 49.5 Mn 30 Co 10 Cr 10 C 0.5 (at.%), could jointly activate the TWIP and TRIP mechanisms to harvest an enhanced strength-ductility combination relative to the interstitial-free reference alloy [5,8,10,12]. However, leaving aside the production of structural components with sophisticated geometry, the precise controlling of metallurgy and subsequent thermomechanical treatments based on the conventional fabrication methods causes significant inefficiency in term of cost and productivity [13].…”

Section: Introductionmentioning

confidence: 99%

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Selective laser melting enabling the hierarchically heterogeneous microstructure and excellent mechanical properties in an interstitial solute strengthened high entropy alloy

Zhu

et al. 2019

Materials Research Letters

149

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An interstitial solute strengthened high entropy alloy (iHEA), Fe 49.5 Mn 30 Co 10 Cr 10 C 0.5 (at.%), was successfully additively manufactured via selective laser melting. The as-built iHEA exhibits a hierarchically heterogeneous microstructure with length scales across several orders of magnitude, which engenders an enhanced strength-ductility combination relative to those fabricated by conventional processing routes. The high yield strength mainly stemmed from the dislocation strengthening besides the friction stress and grain boundary strengthening. The joint activation of multiple deformation mechanisms involving dislocation slip, deformation twinning and phase transformation can maintain the steady work-hardening behavior at high stress levels, leading to a high ductility. IMPACT STATEMENT A hierarchical interstitial high entropy alloy, Fe 49.5 Mn 30 Co 10 Cr 10 C 0.5 (at.%), was successfully additively manufactured via selective laser melting. Its exceptional strength-ductility synergy surpasses that of the most SLM processed conventional alloys.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

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Selective laser melting enabling the hierarchically heterogeneous microstructure and excellent mechanical properties in an interstitial solute strengthened high entropy alloy

Zhu

et al. 2019

Materials Research Letters

149

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“…For example, it has been shown that enriching Co (up to 45%) in CoCrFeNi encourages twinning and martensitic transformation 49 . Also, with a near-zero but positive SFE, the transformation can go both ways and becomes bidirectional 49,50 . Such multiple forward and reverse deformation-driven martensitic transformation events can refine the alloy to a nanolaminate structure and provide extensive work-hardening capacity and material strengthening while retaining good ductility 49 .…”

mentioning

confidence: 99%

Tailoring heterogeneities in high-entropy alloys to promote strength–ductility synergy

2019

Nat Commun

357

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Conventional alloys are usually based on a single host metal. Recent high-entropy alloys (HEAs), in contrast, employ multiple principal elements. The strength of HEAs is considerably higher than traditional solid solutions, as the many constituents lead to a rugged energy landscape that increases the resistance to dislocation motion, which can also be retarded by other heterogeneities. The wide variety of nanostructured heterogeneities in HEAs, including those generated on the fly during tensile straining, also offer elevated strain-hardening capability that promotes uniform tensile ductility. Citing recent examples, this review explores the multiple levels of heterogeneities in multi-principal-element alloys that contribute to lattice friction and back stress hardening, as a general strategy towards strength–ductility synergy beyond current benchmark ranges.

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“…4(c), the kernel average misorientation (KAM) map with the first-nearest neighbor is shown. KAM value is commonly used as an approximate indicator of the density of geometry necessary dislocations (GND) [80,81]. The KAM map in Fig.…”

Section: Alloy I (Cr 20 Mn 24 Fe 30 Co 20 Ni 6 )mentioning

confidence: 99%

Role of magnetic ordering for the design of quinary TWIP-TRIP high entropy alloys

Rao

et al. 2020

Phys. Rev. Materials

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We reveal the impact of magnetic ordering on stacking fault energy (SFE) and its influence on the deformation mechanisms and mechanical properties in a class of nonequiatomic quinary Mn-containing compositional complex alloys or high entropy alloys (HEAs). By combining ab initio simulation and experimental validation, we demonstrate magnetic ordering as an important factor in the activation and transition of deformation modes from planar dislocation slip to TWIP (twinning-induced plasticity) and/or TRIP (transformation-induced plasticity). A wide compositional space of Cr 20 Mn x Fe y Co 20 Ni z (x + y + z = 60, at. %) was probed by density-functional theory calculations to search for potential alloys displaying the TWIP/TRIP effects. Three selected promising HEA compositions with varying Mn concentrations were metallurgically synthesized, processed, and probed for microstructure, deformation mechanism, and mechanical property evaluation. The differences in the deformation modes of the probed HEAs are interpreted in terms of the computed SFEs and their dependence on the predicted magnetic state, as revealed by ab initio calculations and validated by explicit magnetic measurements. It is found that the Mn content plays a key role in the stabilization of antiferromagnetic configurations which strongly impact the SFEs and eventually lead to the prevalent deformation behavior.

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Hierarchical microstructure design to tune the mechanical behavior of an interstitial TRIP-TWIP high-entropy alloy

Cited by 350 publications

References 49 publications

Selective laser melting enabling the hierarchically heterogeneous microstructure and excellent mechanical properties in an interstitial solute strengthened high entropy alloy

Selective laser melting enabling the hierarchically heterogeneous microstructure and excellent mechanical properties in an interstitial solute strengthened high entropy alloy

Tailoring heterogeneities in high-entropy alloys to promote strength–ductility synergy

Role of magnetic ordering for the design of quinary TWIP-TRIP high entropy alloys

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