Dual effects of pre-strain on continuous and discontinuous precipitation of L12-strengthened high-entropy alloys

Fang, Jie; Liu, W.H.; Luan, Junhua; Yang, Tingting; Fu, Ming; Jiao, Zengbao

doi:10.1016/j.jallcom.2022.166730

Cited by 18 publications

(3 citation statements)

References 36 publications

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“…On contrary, the annealing at a higher temperature of 850 °C for 15 h leads to an increase in microhardness only to HV0.05 = 350, which indicates a precipitation hardening effect. Such an increase in the microhardness values of the studied CCA subjected to appropriate heat treatments is associated with the formation of the strengthening L12 precipitates in the FCC(A1) matrix [16][17][18]. There is a potential that such precipitation-strengthened CCAs with L12 may be utilized in high-temperature applications, especially since the strengthening ordered intermetallic phases are largely the same as those in present-generation high-temperature nickel-based superalloys alloys [19].…”

Section: Nanohardness and Vickers Microhardnessmentioning

confidence: 96%

Design, processing and properties of precipitation-hardenable complex concentrated alloy

ULYBKINA,

LAPIN,

KAMYSHNYKOVA

2023

METAL Conference Proeedings

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Complex concentrated alloy (CCA) with nominal composition (CoCrFeNi)92.5Al3Ti4.5 (in at.%) was prepared by vacuum induction melting in a ceramic crucible and tilt cast into the cylindrical ceramic mould. The alloying elements such as Al and Ti were added to the basic quaternary CoCrFeNi system to promote the formation of L12 phase in the FCC (face -centered cubic) matrix during heat treatments. The as-cast ingot was subjected to solid solution annealing, which was followed by free hot forging to refine the coarse columnar grain structure of the as-cast ingot. The forged alloy was subjected to annealing at 800 and 850 °C for 15 h. The properties of the CCA were studied with light microscopy (LM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), nanohardness and microhardness measurements. The CCA solidifies through FCC(A1) primary solidification phase. The as-cast microstructure of the alloy consists of columnar dendritic grains growing from the surface towards the center of the cylindrical ingot. Solution annealing leads to a full chemical homogenization of the alloy and the formation of single-phase coarse columnar grains. Forging leads to the recrystallisation process and formation of equiaxed grains in the forgings. The annealing at the temperatures of 800 and 850 °C leads to significant hardening of the studied alloy, which is associated with the precipitation of L12 particles in the FCC(A1) matrix.

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Section: Nanohardness and Vickers Microhardnessmentioning

confidence: 96%

Design, processing and properties of precipitation-hardenable complex concentrated alloy

ULYBKINA,

LAPIN,

KAMYSHNYKOVA

2023

METAL Conference Proeedings

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“…The sub-grain boundaries would further transform into grain boundaries with the decrease of dislocation density within the sub-grains. Additionally, the pinning effect by the B2 phase at grain boundaries also obstructed the grain growth [41] .…”

Section: Microstructural Evolution During Hip Treatmentmentioning

confidence: 99%

“…It is worth noting that the inhomogeneous deformation (i.e., strain gradient) caused by microstructure heterogeneity produces microscale residual stress and associated back stress, which may provide additional strengthening and strain hardening [39] . During the tensile deformation process, the plastic deformation is first borne by the softer FCC phase, resulting in dislocation accumulation and back stress strengthening at the heterogeneous interface between the FCC and B2 phases, which is why the alloy exhibits high strength characteristics [41] . In addition, the B2 phase gradually undergoes plastic deformation with the increase of tensile deformation.…”

Section: Deformation Mechanismmentioning

confidence: 99%

Hot isostatic pressing induced precipitation strengthening at room and high temperature of Ni-Fe-Cr-Al-V high-entropy alloy manufactured by laser powder bed fusion

Ziwei,

Zhen,

Zheng

et al. 2024

Microstructures

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The highly adjustable properties of high-entropy alloys (HEAs) offer great potential for developing superior materials for critical structural applications in high-temperature conditions. In this study, Ni-Fe-Cr-Al-V HEA was manufactured by laser powder bed fusion, which has a unique microstructure composed of dislocation substructure and Face-centered cubic + L12 coherent structure and achieves the desired strength-ductility combination. Hot isostatic pressing post-treatment was applied on the laser powder bed fusion-processed HEA to further improve the relative density and optimize the mechanical properties. During the hot isostatic pressing process, the precipitation of L12 and B2 phases can be ascribed to the precipitation modes dominated by continuous precipitation and discontinuous precipitation, respectively. With the tensile deformation temperature increasing from 773-1,173 K, the softening degree of HEA increases continuously, and the dominant deformation mechanism evolves from intragranular dislocation slip to grain boundary sliding. At temperatures below 773 K, precipitation strengthening significantly improves tensile strength and ductility. At 1,173 K, the grain boundary strength decreases and grain boundary area increases, which promotes grain boundary sliding and contributes to plastic deformation, resulting in significant softening.

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Hierarchical ferrous medium entropy with heterogeneous precipitates embedded in core-shell grain structure for superior mechanical properties

Kim,

Lee,

Haftlang

et al. 2024

Acta Materialia

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Dual effects of pre-strain on continuous and discontinuous precipitation of L12-strengthened high-entropy alloys

Cited by 18 publications

References 36 publications

Design, processing and properties of precipitation-hardenable complex concentrated alloy

Design, processing and properties of precipitation-hardenable complex concentrated alloy

Hot isostatic pressing induced precipitation strengthening at room and high temperature of Ni-Fe-Cr-Al-V high-entropy alloy manufactured by laser powder bed fusion

Hierarchical ferrous medium entropy with heterogeneous precipitates embedded in core-shell grain structure for superior mechanical properties

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