Microstructure and mechanical properties of equimolar FeCoCrNi high entropy alloy prepared via powder extrusion

Liu, Bin; Wang, Jingshi; Liu, Yong; Fang, Qihong; Wu, Yuan; Chen, Shiqi; Liu, C.T.

doi:10.1016/j.intermet.2016.05.006

Cited by 137 publications

(41 citation statements)

References 30 publications

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“…The FeCoCrNi high entropy alloy was fabricated by powder metallurgical processes, which are detailed in Refs. [33,35], namely, hot extrusion of gas-atomized FeCoCrNi powders. The alloy has a single fcc structure and the average grain size of the asextruded specimen was approximately 35 m. The mechanical properties and microstructure of the alloy at room temperature can be found in Ref.…”

Section: Methodsmentioning

confidence: 99%

“…The alloy has a single fcc structure and the average grain size of the asextruded specimen was approximately 35 m. The mechanical properties and microstructure of the alloy at room temperature can be found in Ref. [35].…”

Section: Methodsmentioning

confidence: 99%

“…Experimental determination of tw is challenging. It has been obtained via identifying the transition point in the work hardening curve [53], or through careful TEM observation on interrupted strained specimens [23,35]. The critical stress for twinning was measured by a few studies using TEM previously, which demonstrates that the critical stress for twinning was independent of temperature and estimated to be ~720 30…”

Section: Critical Stress For Twinning ( Tw)mentioning

confidence: 99%

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Probing deformation mechanisms of a FeCoCrNi high-entropy alloy at 293 and 77 K using in situ neutron diffraction

et al. 2018

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The deformation responses at 77 and 293 K of a FeCoNiCr high-entropy alloy, produced by a powder metallurgy route, are investigated using in situ neutron diffraction and correlative transmission electron microscopy. The strength and ductility of the alloy are significant improved at cryogenic temperatures. The true ultimate tensile strength and total elongation increased from 980 MPa and 45% at 293 K to 1725 MPa and 55% at 77K, respectively. The evolutions of lattice strain, stacking fault probability, and dislocation density were determined via quantifying the in situ neutron diffraction measurements. The results demonstrate that the alloy has a much higher tendency to form stacking faults and mechanical twins as the deformation temperature drops, which is due to the decrease of stacking fault energy (estimated to be 32.5 mJ/m 2 and 13 mJ/m 2 at 293 and 77 K, respectively). The increased volume faction of nanotwins and twin-twin intersections, formed during cryogenic temperature deformation, has been confirmed by transmission electron microscopy analysis. The enhanced strength and ductility at cryogenic temperatures can be attributed to the increased density of dislocations and nano-twins. The findings provide a fundamental understanding of underlying governing mechanistic mechanisms for the twinning induced plasticity in high entropy alloys, paving the way for the development of new alloys with superb resistance to cryogenic environments.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Critical Stress For Twinning ( Tw)mentioning

confidence: 99%

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Probing deformation mechanisms of a FeCoCrNi high-entropy alloy at 293 and 77 K using in situ neutron diffraction

et al. 2018

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“…They usually contain five components ranging from 5% to 35% (atomic percentage, at%). Compared to traditional alloys, the HEAs exhibit various excellent properties in their strength, wear resistance, thermally-stable microstructure, oxidation, and corrosion resistance [2][3][4], indicating large potential applications at high temperature in engineering fields.…”

Section: Introductionmentioning

confidence: 99%

Microstructures and Tribological Properties of TiC Reinforced FeCoNiCuAl High-Entropy Alloy at Normal and Elevated Temperature

Zhu

Zhou

et al. 2020

Metals

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Recent studies have suggested that high-entropy alloys (HEAs) possess high fracture toughness, good wear resistance, and excellent high-temperature mechanical properties. In order to further improve their properties, a batch of TiC-reinforced FeCoNiCuAl HEA composites were fabricated by mechanical alloying and spark plasma sintering. X-ray diffractometry analysis of the TiC-reinforced HEA composites, combined with scanning electron microscopy imaging, indicated that TiC particles were uniformly distributed in the face-centered cubic and body-centered cubic phases. The room temperature hardness of the FeCoNiCuAl HEA was increased from 467 to 768 HV with the addition of TiC, owing to precipitation strengthening and fine grain strengthening effects. As the TiC content increased, the friction coefficient of the FeCoNiCuAl HEA first increased and then decreased at room temperature, due to the transition of the wear mechanism from adhesive to abrasive behavior. At higher temperature, the friction coefficient of the FeCoNiCuAl HEA monotonously reduced, corresponding well with the transition from adhesive wear to oxidative wear.wear resistance of HEAs [8,9]. Recently, it was reported that the addition of Cu can reduce the wear rate of CoCrFeNiCux HEAs at both room temperature and elevated temperatures, and wear resistance at elevated temperatures is promoted more significantly than that at room temperature due to their self-lubricating mechanism [10].However, the major challenge for practical applications of the FeCoNiCuAl HEA is its insufficient strength. Recent studies have indicated that the precipitation of reinforcing phases in various materials, such as HEAs and ceramics, can further increase the yield strength of the alloy while maintaining relatively high ductility [11][12][13]. For instance, the precipitation of SiC nanoparticles in FeCoCrNiMn enhanced the compressive yield strength from 1180 to 1480 MPa at room temperature [14]. The precipitation of WC in the FeCoCrNi HEA leads to an improved hardness up to 768HV, which corresponds well with the transition of the wear mechanism [13]. The alloy may also be strengthened by dispersion strengthening, which can significantly improve the strength and hardness of the alloy, and reduce the plasticity and toughness slightly [15]. TiC is considered a good candidate as the strengthening phase due to its high melting point, high hardness, low density, good metal matrix wettability, good chemical stability, and excellent wear resistance [16]. The optimized yield strength of the (FeCrNiCo)Al 0.75 Cu 0.25 HEA reinforced by TiC particles can reach 1637 MPa, which is increased by 90.6% compared to the (FeCrNiCo)Al 0.75 Cu 0.25 HEA [17]. However, the precipitation of ceramic nanoparticles in the metal matrix tends to be unevenly distributed, which is probably originated from the instability of the interfaces between the ceramic particles and the metal matrix [18][19][20]. In order to make the second phase uniformly distributed in the matrix, in situ methods are widely used to fa...

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“…As a typical HEA, quaternary FeCoCrNi HEA with a simple FCC solid solution was wildly investigated. Liu et al [16] reported that the FeCoCrNi HEA is characterized by a high tensile strength of 712.5 MPa and a high elongation of 56%, indicating excellent deformation and work hardening capacity. Such good machinability makes it a reliable base for further strengthing with the addition of other principal elements.…”

Section: Introductionmentioning

confidence: 99%

Microstructure and Wear Behavior of FeCoCrNiMo0.2 High Entropy Coatings Prepared by Air Plasma Spray and the High Velocity Oxy-Fuel Spray Processes

Liu

et al. 2017

Coatings

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Abstract:In the present research, the spherical FeCoCrNiMo0.2 high entropy alloy (HEA) powders with a single FCC solid solution structure were prepared by gas atomization. Subsequently, the FeCoCrNiMo0.2 coatings with a different content of oxide inclusions were prepared by air plasma spraying (APS) and high-velocity oxy-fuel spraying (HVOF), respectively. The microstructure, phase composition, mechanical properties, and tribological behaviors of these HEA coatings were investigated. The results showed that both HEA coatings showed a typical lamellar structure with low porosity. Besides the primary FCC phase, a mixture of Fe 2 O 3 , Fe 3 O 4 , and AB 2 O 4 (A = Fe, Co, Ni, and B = Fe, Cr) was identified as the oxide inclusions. The oxide content of the APS coating and HVOF coating was calculated to be 47.0% and 12.7%, respectively. The wear resistance of the APS coating was approximately one order of magnitude higher than that of the HVOF coating. It was mainly attributed to the self-lubricated effect caused by the oxide films. The mass loss of the APS coating was mainly ascribed to the breakaway of the oxide film, while the main wear mechanism of the HVOF coating was the abrasive wear.

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Microstructure and mechanical properties of equimolar FeCoCrNi high entropy alloy prepared via powder extrusion

Cited by 137 publications

References 30 publications

Probing deformation mechanisms of a FeCoCrNi high-entropy alloy at 293 and 77 K using in situ neutron diffraction

Probing deformation mechanisms of a FeCoCrNi high-entropy alloy at 293 and 77 K using in situ neutron diffraction

Microstructures and Tribological Properties of TiC Reinforced FeCoNiCuAl High-Entropy Alloy at Normal and Elevated Temperature

Microstructure and Wear Behavior of FeCoCrNiMo0.2 High Entropy Coatings Prepared by Air Plasma Spray and the High Velocity Oxy-Fuel Spray Processes

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Microstructure and mechanical properties of equimolar FeCoCrNi high entropy alloy prepared via powder extrusion

Cited by 137 publications

References 30 publications

Probing deformation mechanisms of a FeCoCrNi high-entropy alloy at 293 and 77 K using in situ neutron diffraction

Probing deformation mechanisms of a FeCoCrNi high-entropy alloy at 293 and 77 K using in situ neutron diffraction

Microstructures and Tribological Properties of TiC Reinforced FeCoNiCuAl High-Entropy Alloy at Normal and Elevated Temperature

Microstructure and Wear Behavior of FeCoCrNiMo0.2 High Entropy Coatings Prepared by Air Plasma Spray and the High Velocity Oxy-Fuel Spray Processes

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Probing deformation mechanisms of a FeCoCrNi high-entropy alloy at 293 and 77 K using in situ neutron diffraction

Probing deformation mechanisms of a FeCoCrNi high-entropy alloy at 293 and 77 K using in situ neutron diffraction