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Development and characterization of graphene-reinforced Inconel 825 composite alloy for high temperature applications

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30 juin 2025
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Figure 1

(a) SEM image of a specimen with compositions of Inconel 825, tungsten carbide (WC), cobalt (Co), and nanographene (Gr) powder. (b) Energy dispersive X-ray analysis (EDAX) spectrum of powder.
(a) SEM image of a specimen with compositions of Inconel 825, tungsten carbide (WC), cobalt (Co), and nanographene (Gr) powder. (b) Energy dispersive X-ray analysis (EDAX) spectrum of powder.

Figure 2

Image of tensile specimen.
Image of tensile specimen.

Figure 3

(a–d) Specimen prepared via SPS method. (a) Layer-by-layer sintered specimen (94.85 wt% Inconel–4.5 wt% WC–0.5 wt% Co–0.15 wt% Gr), (b) uniformly mixed specimen (45 wt% Inconel–10 wt% WC–33 wt% Co–12 wt% Gr), (c) high cobalt content specimen (33 wt% Inconel–10 wt% WC–45 wt% Co–12 wt% Gr), and (d) high Inconel content specimen (90 wt% Inconel–4 wt% WC–5 wt% Co–1 wt% Gr).
(a–d) Specimen prepared via SPS method. (a) Layer-by-layer sintered specimen (94.85 wt% Inconel–4.5 wt% WC–0.5 wt% Co–0.15 wt% Gr), (b) uniformly mixed specimen (45 wt% Inconel–10 wt% WC–33 wt% Co–12 wt% Gr), (c) high cobalt content specimen (33 wt% Inconel–10 wt% WC–45 wt% Co–12 wt% Gr), and (d) high Inconel content specimen (90 wt% Inconel–4 wt% WC–5 wt% Co–1 wt% Gr).

Figure 4

SEM image of a single particle of Inconel 825.
SEM image of a single particle of Inconel 825.

Figure 5

Optical metallographic image (magnification of 200×) of a powder particle sintered etched cross-section showing the microstructure of (a) uniformly mixed specimen (45 wt% Inconel–10 wt% WC–33 wt% Co–12 wt% Gr), (b) high cobalt content specimen (33 wt% Inconel–10 wt% WC–45 wt% Co–12 wt% Gr), and (c) high Inconel content specimen (90 wt% Inconel–4 wt% WC–5 wt% Co–1 wt% Gr).
Optical metallographic image (magnification of 200×) of a powder particle sintered etched cross-section showing the microstructure of (a) uniformly mixed specimen (45 wt% Inconel–10 wt% WC–33 wt% Co–12 wt% Gr), (b) high cobalt content specimen (33 wt% Inconel–10 wt% WC–45 wt% Co–12 wt% Gr), and (c) high Inconel content specimen (90 wt% Inconel–4 wt% WC–5 wt% Co–1 wt% Gr).

Figure 6

SEM of specimens for phase distribution and grain boundaries: after sintering, (a and b) 45 wt% Inconel, 10 wt% WC, 33 wt% Co, and 12 wt% graphene; (c and d) 33 wt% Inconel, 10 wt% WC, 45 wt% Co, and 12 wt% grapheme, and (e and f) 90 wt% Inconel, 4 wt% WC, 5 wt% Co & 1 wt% graphene.
SEM of specimens for phase distribution and grain boundaries: after sintering, (a and b) 45 wt% Inconel, 10 wt% WC, 33 wt% Co, and 12 wt% graphene; (c and d) 33 wt% Inconel, 10 wt% WC, 45 wt% Co, and 12 wt% grapheme, and (e and f) 90 wt% Inconel, 4 wt% WC, 5 wt% Co & 1 wt% graphene.

Figure 7

(a) 90 wt% Inconel, 4 wt% WC, 5 wt% Co, and 1 wt% graphene. EDAX element mapping in specimen D. (b) 45 wt% Inconel, 10 wt% WC, 33 wt% Co, and 12 wt% graphene. (c) 33 wt% Inconel, 10 wt% WC, 45 wt% Co, and 12 wt% graphene.
(a) 90 wt% Inconel, 4 wt% WC, 5 wt% Co, and 1 wt% graphene. EDAX element mapping in specimen D. (b) 45 wt% Inconel, 10 wt% WC, 33 wt% Co, and 12 wt% graphene. (c) 33 wt% Inconel, 10 wt% WC, 45 wt% Co, and 12 wt% graphene.

Figure 8

(a)–(h) EDAX area color mapping of the sample with 90 wt% Inconel, 4 wt% WC, 5 wt% Co, and 1 wt% graphene.
(a)–(h) EDAX area color mapping of the sample with 90 wt% Inconel, 4 wt% WC, 5 wt% Co, and 1 wt% graphene.

Figure 9

Relation between the micro-hardness and relative density of compositions A, B, C, and D.
Relation between the micro-hardness and relative density of compositions A, B, C, and D.

Figure 10

(a) Stress–strain curve of the samples tested at ambient temperature and (b) ultimate tensile strength and tensile modulus of the samples at ambient temperature.
(a) Stress–strain curve of the samples tested at ambient temperature and (b) ultimate tensile strength and tensile modulus of the samples at ambient temperature.

Figure 11

(a) Stress–strain curve at 450°C. (b) Ultimate tensile strength and tensile modulus of compositions A, B, C, and D at 450°C.
(a) Stress–strain curve at 450°C. (b) Ultimate tensile strength and tensile modulus of compositions A, B, C, and D at 450°C.

Figure 12

(a) SEM morphology of the fracture surface area of specimen D at room temperature. (b) Specimen D at 450°C.
(a) SEM morphology of the fracture surface area of specimen D at room temperature. (b) Specimen D at 450°C.

Processing parameters for sintering the composites_

Sintering details
Alloy/composites (wt%) Temperature (°C) Pressure (MPa) Heating rate (°C/min) Wetting time (min)
45% Inconel, 10% WC, 33% Co, and 12% Gr 950 40 100 5
33% Inconel, 10% WC, 45% Co, and 12% Gr 1,000 45 100 5
90 wt% Inconel, 4 wt% WC, 5 wt% Co, and 1 wt% Gr 1,050 50 100 5

Trials of micro tensile test on specimens A, B, C, and D_ Bold value significantly shows the Specimen D tensile stress is maximum_

Specimen Maximum tensile stress at ambient temperature (MPa) Maximum tensile stress at 450°C temperature (MPa)
Trial 1 Trial 2 Trial 3 Average Trial 1 Trial 2 Trial 3 Average
A 741 701 689.7 710.6 674.5 640.9 624 646.5
B 336.3 346 386 356.1 362.3 336 311 336.4
C 496.3 463 511 490.1 425.3 384.2 399.8 403.1
D 763.4 673.4 729.8 722.2 691.1 611.2 688.7 663.6

Micro-hardness and relative density percentages of sintered composites_

Notation of specimen Hardness (HV) Relative density (%)
A 368 ± 3 96.7 ± 0.3
B 340 ± 3 94.6 ± 0.4
C 380 ± 4 97.8 ± 0.2
D 370 ± 3 97.0 ± 0.3