Effect of heat treatments on microstructure and mechanical properties of Al0.5CoCrFeNi complex concentrated alloy

Lapin, J.; Makwana, M.; Klimová, A.

doi:10.4149/km_2021_2_79

Cited by 3 publications

(2 citation statements)

References 36 publications

(54 reference statements)

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“…6d shows the formation of elongated particles oriented nearly perpendicularly to the load axis in the BCC(B2)/BCC(A2) region. The same particles were found in the BCC(B2)/BCC(A2) region in ascast Al 0.5 CoCrFeNi alloy and identified to belong to the FCC(A1) phase [32]. More intense precipitation of ductile FCC(A1) particles in BCC(B2)/BCC(A2) region and inhomogeneous precipitation of BCC(B2) in FCC(A1) dendrite matrix occur during tensile deformation at 900 • C. Formation of needle-like BCC(B2) precipitates due to high-temperature tensile loading within FCC(A1) matrix with composition given in Table 1 was observed recently by Lapin et al [47] in DS Al 0.5 CoCr 1.3 FeNi 1.3 (Ti, Si, B, C) 0.3 alloy.…”

Section: Numerical Simulation Of Tensile and Compression Testssupporting

confidence: 59%

High temperature deformation behaviour of as-cast Al0.4Co0.9Cr1.2Fe0.9Ni1.2(Si, Ti, C, B)0.375 complex concentrated alloy during tensile and compression tests

Štamborská,

Pelachová

2023

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The deformation behaviour of as-cast Al0.4Co0.9Cr1.2Fe0.9Ni1.2(Si, Ti, C, B)0.375 complex concentrated alloy (CCA) in the temperature range from 700 up to 900 • C during tensile and compression tests was studied. The as-cast alloy was prepared by vacuum induction melting in a ceramic crucible followed by a tilt casting to a graphite mould. Highly anisotropic microstructure of tensile and compression specimens taken from the as-cast ingot consisted of 89 vol.% of columnar FCC(A1) (face-centred cubic crystal structure A1) dendrites and 11 vol.% of the multiphase interdendritic region where ordered phases as Cr2B, TiC, BCC(B2) (ordered body-centred cubic crystal structure B2) + BCC(A2) (disordered body-centred cubic crystal structure A2), and lamellar eutectic composed of FCC(A1) + G -(Ni,Co,Fe)16(Ti,Cr)6(Si,Al)7 (cubic face-centred crystal structure) phase were formed during solidification. Columnar FCC(A1) dendrite grains were oriented at an angle ranging from 60 • to 90 • to the longitudinal axis of the test specimens.The value of 0.2 % offset yield strength decreases with increasing applied temperature, at 700 • C tension and compression, it was measured to be about (429 ± 3) MPa and at 900 • C it decreased to the value of about (90 ± 5) MPa. The alloy during tensile deformation at 700 • C shows the strain hardening stage up to fracture. The tensile deformation true strain-true stress curves at 800 • C and compression deformation true strain-true stress curves at temperatures from 700 to 800 • C show the strain hardening stage at initial strains. After reaching the peak values, the strain softening stage is typical for the alloy. The strain softening stage results from partial dynamic recrystallisation of FCC(A1) dendrites and fracture of brittle high elastic modulus phases in the interdendritic region. The compression and tensile curves at the temperature of 900 • C show a short area of the strain hardening stage, followed by a steady-state deformation at a constant flow stress. The finite element analysis (FEA) of the 3D distribution of local equivalent strains corresponds qualitatively to the observed structural changes within the necked and barrelled specimens. K e y w o r d s : complex concentrated alloys, microstructure, numerical modelling, mechanical properties, fracture

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Section: Numerical Simulation Of Tensile and Compression Testssupporting

confidence: 59%

High temperature deformation behaviour of as-cast Al0.4Co0.9Cr1.2Fe0.9Ni1.2(Si, Ti, C, B)0.375 complex concentrated alloy during tensile and compression tests

Štamborská,

Pelachová

2023

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“…The CCAs are also compositionally complex alloys but the rules concerning the number of elements and coexisting phases, concentration range, and magnitude or importance of configurational entropy satisfy not only to HEA definition but also include many other alloys including concentrated ternary and quaternary alloys. It has been reported that CCAs based on quaternary Co-Cr-Fe-Ni can serve as a good base for the design of CCAs strengthened by intermetallic and ceramic phases for high-temperature structural applications [12]. He et al [13] have reported outstanding tensile properties of the alloy with nominal composition (FeCoNiCr)94Ti2Al4 (at.%), which has been achieved by precipitation of nanosized L12-Ni3(Ti, Al) particles in CoCrFeNi HEA matrix.…”

Section: Introductionmentioning

confidence: 99%

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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Influence of hot forging on grain formation in Al0.35CoCrFeNi high-entropy alloy: numerical simulation, microstructure and mechanical properties

Štamborská,

Pelachová,

Danko

et al. 2024

Arch. Civ. Mech. Eng.

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One-step (F100) and three-step (F30-60-40) hot forging of Al0.35CoCrFeNi alloy was investigated to achieve a uniform equiaxed grain structure. In the as-cast and forged state, only a single-phase face-centered cubic structure was observed. The formation of twins, recrystallized and partially recrystallized grains in the volume of the samples was observed depending on used forging process. To predict uniform grain-size formation numerical simulation of the hot-forging process was used. The numerical model was calibrated and validated by means of measured compression experimental data of as-cast Al0.35CoCrFeNi alloy before forging. Thermal analysis using finite element analysis was used to simulate cooling of sample during the relocation from the furnace on the lower die. Simulations were run under different thermo-mechanical conditions and the regions for the formation of dynamically recrystallized grains were predicted. Room temperature mechanical properties were evaluated after F100 and F30-60-40 hot-forging process. The F30-60-40 hot forging optimized the grain size, which was evident in the very small dispersion of the room temperature mechanical properties in tension. Elongation after F30-60-40 hot forging increased by 17%. The correlation between temperature, equivalent stress, equivalent plastic strain, microstructure, tensile properties, and strain-hardening behavior is discussed.

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Effect of heat treatments on microstructure and mechanical properties of Al0.5CoCrFeNi complex concentrated alloy

Cited by 3 publications

References 36 publications

High temperature deformation behaviour of as-cast Al0.4Co0.9Cr1.2Fe0.9Ni1.2(Si, Ti, C, B)0.375 complex concentrated alloy during tensile and compression tests

High temperature deformation behaviour of as-cast Al0.4Co0.9Cr1.2Fe0.9Ni1.2(Si, Ti, C, B)0.375 complex concentrated alloy during tensile and compression tests

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

Influence of hot forging on grain formation in Al0.35CoCrFeNi high-entropy alloy: numerical simulation, microstructure and mechanical properties

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