Precipitation phase and twins strengthening behaviors of as-cast non-equiatomic CoCrFeNiMo high entropy alloys

Gao, Xuefeng; Liu, Tong; Zhang, Xiaofu; Fang, Hongyuan; Qin, Guoliang; Chen, Ruirun

doi:10.1016/j.jallcom.2022.165584

Cited by 28 publications

(6 citation statements)

References 72 publications

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“…Figure shows the TEM morphology of the surface and subsurface of the Al 10 Cr 28 Co 28 Ni 34 HEA coating after CE for 10 h. It was not difficult to find that a large number of dislocation and deformation twins with the [011̅] axis induced by cavitation load were indeed generated in the subsurface of Al 10 Cr 28 Co 28 Ni 34 HEA coating after CE for 10 h (Figure C,D). According to the dynamic Hall–Petch effect, the formation of twins introduced additional interfaces into the original grains, which was able to hinder dislocation movement and slippage to form a dislocation plug. − If these defects were allowed to accumulate and develop, hard embrittlement and fatigue spalling on the material surface would inevitably occur. Fortunately, cavitation heat could promote grain growth and relaxation recovery of these refined grains and distorted structure on the surface (Figure A,B), thus effectively avoiding excessive enrichment of defective structures and hard embrittlement of the surface, which was crucial for inhibiting material stripping.…”

Section: Discussionmentioning

confidence: 99%

Design of High-Entropy Alloy Coating for Cavitation Erosion Resistance by Different Energy-Induced Dynamic Cyclic Behaviors

Cao

Hou

et al. 2023

ACS Appl. Mater. Interfaces

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The dispute over the effect of cavitation heat on material surface intensifies the fuzziness of cavitation erosion (CE) mechanism and limits the development of protective materials. Here, an anti-CE Al 10 Cr 28 Co 28 Ni 34 high-entropy alloy (HEA) coating with single face-centered cubic (FCC), prepared by high-velocity oxy-fuel (HVOF) spraying technologies, was designed by inducing mechanical and thermal energy-induced behaviors to transform or counteract each other. The results showed that, on the one hand, this coating underwent the refinement of the average grain size from 1.22 to 1.02 μm, the increase in dislocation density from 1.28 × 10 −10 to 1.83 × 10 −10 m −2 , and the martensitic transformation from FCC to body-centered cubic (BCC) under the cavitation load; on the other hand, cavitation heat could indeed induce grain growth and realize structural relaxation, which confirmed that cavitation heat acting on the material surface at temperatures theoretically above 1206.28 K also played a significant role in the CE mechanism. That is, the surface microstructure of this coating was always in a dynamic cycle during the CE process. Therefore, the coating achieved the simultaneous absorption of mechanical impact energy and thermal energy released by the bubble collapse while effectively avoiding the overenrichment of crystal defects and finally exhibited a CE resistance 2 times better than that of the classical AlCrCoFeNi HEA coating. This design concept of inducing different energy restraints or neutralization through the special response behaviors of surface microstructure provides a completely new way for the development of CE-resistant materials.

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Section: Discussionmentioning

confidence: 99%

Design of High-Entropy Alloy Coating for Cavitation Erosion Resistance by Different Energy-Induced Dynamic Cyclic Behaviors

Cao

Hou

et al. 2023

ACS Appl. Mater. Interfaces

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“…The chemically disordered complex structure inherent in high-entropy alloys also reduces the mean free path of atoms, increases the probability of point defect recombination, and lowers the vacancy supersaturation concentration. [50][51][52] This decrease in vacancy flux to the helium bubbles, coupled with inhibited helium atom mobility, leads to a reduction in the growth of the helium bubbles in multiple components and dual-phase HEAs. So that the sizes and density of helium bubbles in the present γ and γ dual-phase FeCoNiCr(Ni 3 Ti) 0.1 HEAs are smaller than those in singlephase FeCoNiCr.…”

Section: Coherent Nanoprecipitatesmentioning

confidence: 99%

Evolution of helium bubbles in FeCoNiCr-based high-entropy alloys containing γ′ nanoprecipitates

Feng 冯,

Jiang 蒋,

Hu 胡

et al. 2024

Chinese Phys. B

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A series of high-entropy alloys (HEAs) containing nanoprecipitates of varying sizes were successfully prepared by a non-consuming vacuum arc melting method. In order to study the irradiation evolution of helium bubbles in the FeCoNiCr-based HEAs with γ' precipitates, samples were irradiated with 100 keV helium ions to a fluence of 5 × 1020 ions/m2 at 293 K and 673 K. And the room temperature irradiated samples were annealed at different temperatures to examine the diffusion behavior of helium bubbles. Transmission electron microscope (TEM) was employed to characterize the structural morphology of precipitated nanoparticles and the evolution of helium bubbles. Experimental results reveal that nanosized, spherical, dispersed, coherent and ordered L12-type Ni3Ti γ' precipitations were introduced in FeCoNiCr(Ni3Ti)0.1 HEAs by means of ageing treatments at temperatures between 1073-1123 K. Under the ageing treatment conditions applied in this work, γ' nanoparticles were precipitated in FeCoNiCr(Ni3Ti)0.1 HEAs with average diameters of 15.80 nm, 37.00 nm and 62.50 nm, respectively. The average sizes of helium bubbles observed in samples after 673 K irradiation were 1.46 nm, 1.65 nm and 1.58 nm, respectively. The improvement in the irradiation resistance of FeCoNiCr(Ni3Ti)0.1 HEAs was evidenced by the diminution in bubbles size. Furthermore, FeCoNiCr(Ni3Ti)0.1 HEAs containing γ' precipitates of 15.8 nm exhibited the minimum size and density of He bubbles, which can be ascribed to the considerable helium trapping effects of heterogeneous coherent phase boundaries. Subsequently, annealing experiments conducted after 293 K irradiation indicate that HEAs containing precipitated phases exhibit smaller apparent activation energies (Ea) for helium bubbles, resulting in larger helium bubble sizes. This study provides guidance on improving the irradiation resistance of L12-strengthened high-entropy alloys.

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“…However, a key bottleneck that hinders their widespread applications is the traditional strength-ductility trade-off [7] . It was recently reported that dual-phase compositionally complex alloys (CCAs) could overcome this hurdle [8][9][10][11][12] . The dualphase non-equiatomic FeMnCoCr CCA contains face-centered cubic (FCC) γ and hexagonal close-packed (HCP) ε phases, which are obtained by successive cold rolling, annealing above 900 °C and water quenching [8] .…”

Section: Introductionmentioning

confidence: 99%

“…The dualphase non-equiatomic FeMnCoCr CCA contains face-centered cubic (FCC) γ and hexagonal close-packed (HCP) ε phases, which are obtained by successive cold rolling, annealing above 900 °C and water quenching [8] . Owing to the metastable FCC γ and stable HCP ε phases at room temperature, the mechanical deformation can actively promote the transformation from FCC γ to HCP ε phase [4,5,11] . Such a phase transformation mainly contributes to the work hardening and thus optimizes the strength and ductility simultaneously.…”

Section: Introductionmentioning

confidence: 99%

Detwinning/twin growth-induced phase transformation in a metastable compositionally complex alloy

Lu¹,

An²,

Liebscher³

2022

Microstructures

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Extensive experiments have shown that the transformation from the face-centered cubic to hexagonal close-packed ε phase usually occurs around coherent Σ3 boundaries. However, in this letter, we reveal a different transformation mechanism in a metastable dual-phase compositionally complex alloy via a systematic high-resolution scanning transmission electron microscopy analysis. The face-centered cubic γ matrix can be transformed to the hexagonal close-packed ɛ phase (as small as one unit) around an incoherent Σ3 boundary (~30 nm), i.e., the facet of the coherent Σ3 boundary. This transformation is assisted by the detwinning/twin growth of a coherent Σ3 boundary during annealing treatment (900 °C for 60 min).

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Precipitation phase and twins strengthening behaviors of as-cast non-equiatomic CoCrFeNiMo high entropy alloys

Cited by 28 publications

References 72 publications

Design of High-Entropy Alloy Coating for Cavitation Erosion Resistance by Different Energy-Induced Dynamic Cyclic Behaviors

Design of High-Entropy Alloy Coating for Cavitation Erosion Resistance by Different Energy-Induced Dynamic Cyclic Behaviors

Evolution of helium bubbles in FeCoNiCr-based high-entropy alloys containing γ′ nanoprecipitates

Detwinning/twin growth-induced phase transformation in a metastable compositionally complex alloy

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