Superior tensile properties of 1%C-CoCrFeMnNi high-entropy alloy additively manufactured by selective laser melting

Park, Jeong Min; Choe, Jungho; Kim, Jung Gi; Bae, Jae Wung; Moon, Jongun; Yang, Sangsun; Kim, Young Ho; Yu, Juan; Kim, Hyoung Seop

doi:10.1080/21663831.2019.1638844

Cited by 158 publications

(53 citation statements)

References 27 publications

(58 reference statements)

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“…All elements among the cells are uniformly distributed without apparent segregation(Figure 1(h)). No carbides, as observed in the SLM processed carbon-doped CoCrFeNiMn[17], could be detected. Instead, a few Al-rich oxides formed along cellular boundaries due to the oxidation of Al impurity(Figure 4).…”

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confidence: 74%

“…During SLM, the highly localized melting/solidification enables the formation of a hierarchically metastable microstructure that is not accessible through the conventional metallurgical methods, engendering excellent mechanical properties [14,15]. However, as one of most versatile additive manufacturing technologies, the application of SLM to prepare HEAs is still limited [16][17][18]. Herein, we employed SLM to fabricate the carbon-doped iHEA to investigate its printability, microstructures, tensile properties and deformation mechanisms.…”

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

146

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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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confidence: 74%

Section: Introductionmentioning

confidence: 99%

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

146

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“…%) are subject to cold-rolling followed by recrystallization, large volume fractions of carbides are often present as well as changes in grain size. The carbide's effect on the mechanical properties in addition to the reduction in solute strengthening from the reduction in carbon in solution [30][31][32][33][34] make it infeasible to determine the solid-solution strengthening effect of the carbon. CoCrFeMnNi with very high carbon contents (2.2-8.9 at.…”

Section: T (K)mentioning

confidence: 99%

Interstitials in f.c.c. High Entropy Alloys

Baker

2020

Metals

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The effects of interstitials on the mechanical properties of single-phase f.c.c. high entropy alloys (HEAs) have been assessed based on a review of the literature. It is found that in nearly all studies, carbon increases the yield strength, in some cases by more than in traditional alloys. This suggests that carbon can be an excellent way to strengthen HEAs. This strength increase is related to the lattice expansion from the carbon. The effects on other mechanical behavior is mixed. Most studies show a slight reduction in ductility due to carbon, but a few show increases in ductility accompanying the yield strength increase. Similarly, some studies show little or modest increases in work-hardening rate (WHR) due to carbon, whereas a few show a substantial increase. These latter effects are due to changes in deformation mode. For both undoped and carbon doped CoCrFeMnNi, the room temperature ductility decreases slightly with decreasing grain size until ~2–5 µm, below which the ductility appears to decrease rapidly. The room temperature WHR also appears to decrease with decreasing grain size in both undoped and carbon-doped CoCrFeMnNi and in nitrogen-doped medium entropy alloy NiCoCr, and, at least for the undoped HEA, shows a sharp decrease at grain sizes <2 µm. Interestingly, carbon has been shown to almost double the Hall–Petch strengthening in CoCrFeMnNi, suggesting the segregation of carbon to the grain boundaries. There have been few studies on the effects of other interstitials such as boron, nitrogen and hydrogen. It is clear that more research is needed on interstitials both to understand their effects on mechanical properties and to optimize their use.

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“…However, many FCC single-phase HEAs generally show insufficient strength for engineering applications [6]. To overcome this drawback, precipitation hardening [7,8], interstitial solute strengthening [9,10], heterogeneous grain structure [11,12] or multi-phase structure [13] have been applied. Especially, body-centered cubic (BCC) plus FCC dual-phase (DP) or multi-phase HEAs can achieve excellent strength-ductility combinations [14].…”

Section: Introductionmentioning

confidence: 99%

Tailored microstructures and strengthening mechanisms in an additively manufactured dual-phase high-entropy alloy via selective laser melting

Luo

Wang

2020

Sci. China Mater.

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Dual-phase high-entropy alloys (DP-HEAs) with excellent strength-ductility combinations have attracted scientific interests. In the present study, the microstructures of AlCrCuFeNi 3.0 DP-HEA fabricated via selective laser melting (SLM) are rationally adjusted and controlled. The mechanisms engendering the hierarchical microstructures are revealed. It is found that the AlCrCuFeNi 3.0 fabricated by SLM at the scanning speed of 400 mm s −1 falls into the eutectic coupled zone, and increasing the scanning speed will make this composition deviate away from the eutectic coupled zone due to the increased cooling rate. The enrichment of Cr and Fe solutes with large growth restriction values ahead of the solid/ liquid interface can develop a constitutional supercooling zone, thus facilitating the heterogeneous nucleation and nearequiaxed grain formation. The synergy of the near-eutectic DP nano-structures and near-equiaxed grains instead of columnar ones effectively suppresses cracking for the as-built DP-HEA.During the tensile deformation, the intergranular back stress hardening similar to the grain-boundary strengthening is discovered. Meanwhile, the near-eutectic microstructures comprised of soft face-centered cubic and hard ordered bodycentered cubic (B2) DP nano-structures lead to plastic strain incompatibility within grains, thus producing the intragranular back stress. The Cr-rich nano-precipitates inside the B2 phase are found to be sheared by dislocation gliding and can complement the back stress. Additionally, multiple strengthening mechanisms are physically evaluated, and the back stress strengthening contributes obviously to the high performances of the as-built DP-HEA.

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Superior tensile properties of 1%C-CoCrFeMnNi high-entropy alloy additively manufactured by selective laser melting

Abstract: Kim (2020) Superior tensile properties of 1%C-CoCrFeMnNi high-entropy alloy additively manufactured by selective laser melting,

Cited by 158 publications

References 27 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

Interstitials in f.c.c. High Entropy Alloys

Tailored microstructures and strengthening mechanisms in an additively manufactured dual-phase high-entropy alloy via selective laser melting

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