Author Affiliations
Key Laboratory for Materials Modification by Laser, Ion, and Electron Beams, Ministry of Education, Dalian University of Technology, Dalian 116024, Liaoning, Chinashow less
Fig. 1. X-ray diffraction patterns of as-deposited alloys with different compositions
Fig. 2. Typical microstructural morphologies of as-deposited alloys with different compositions. (a) Ni75.0Cr25.0alloy; (b) Ni75.0Cr18.75Al6.25alloy; (c) Ni75.0Cr12.5Al12.5alloy; (d) Ni75.0Cr6.25Al18.75alloy; (e) Ni75.0Al25.0alloy
Fig. 3. TEM images taken from as-deposited Ni75.0Cr12.5Al12.5 alloy. (a) Bright-field image of γ′-Ni3Al phase; (b) electron diffraction pattern of γ′-Ni3Al phase
Fig. 4. Influence of Al content on microhardness of as-deposited alloys
Fig. 5. Compressive stress-strain curves of as-deposited alloys with different compositions
Fig. 6. Typical compressed surface morphologies of as-deposited alloys with different compositions. (a) Ni75.0Cr25.0alloy; (b) Ni75.0Cr18.75Al6.25alloy; (c) Ni75.0Cr12.5Al12.5alloy; (d) Ni75.0Cr6.25Al18.75alloy; (e) Ni75.0Al25.0alloy
Fig. 7. Continuous variable-temperature oxidation kinetic curves of as-deposited alloys with different compositions
Fig. 8. Oxidized surface morphologies of as-deposited alloys with different compositions. (a) Ni75.0Cr25.0 alloy; (b) Ni75.0Cr18.75Al6.25 alloy; (c) Ni75.0Cr12.5Al12.5 alloy; (d) Ni75.0Cr6.25Al18.75 alloy; (e) Ni75.0Al25.0 alloy
Fig. 9. X-ray diffraction patterns of oxidized surfaces of as-deposited alloys with different compositions
Fig. 10. Low magnification microstructure of as-deposited alloys. (a)(b)(c) Ni75.0Cr25.0 alloy; (d)(e)(f) Ni75.0Cr18.75Al6.25 alloy; (g)(h)(i) Ni75.0Cr12.5Al12.5 alloy; (j)(k)(l) Ni75.0Cr6.25Al18.75 alloy; (m)(n)(o) Ni75.0Al25.0 alloy
Fig. 11. DSC thermal curves of as-deposited alloys with different compositions
Cluster formula | Atomic fraction /% |
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Ni | Cr | Al |
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[Cr-Ni12]Cr3 | 75.0 | 25.00 | 0 | [Al-Ni12]Cr3 | 75.0 | 18.75 | 6.25 | [Al-Ni12] Al1Cr2 | 75.0 | 12.50 | 12.50 | [Al-Ni12] Al2Cr1 | 75.0 | 6.25 | 18.75 | [Al -Ni12] Al3 | 75.0 | 0 | 25.00 |
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Table 1. Chemical compositions of alloys
Alloy | aγ /nm | aγ′ /nm | δγ′/γ /% |
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Ni75.0Cr25.0 | 0.3558±0.0002 | - | - | Ni75.0Cr18.75Al6.25 | 0.3571±0.0003 | - | - | Ni75.0Cr12.5Al12.5 | 0.3564±0.0001 | 0.3567±0.0002 | 0.07±0.02 | Ni75.0Cr6.25Al18.75 | 0.3566±0.0002 | 0.3572±0.0001 | 0.17±0.03 | Ni75.0Al25.0 | 0.3563±0.0002 | 0.3573±0.0001 | 0.28±0.03 |
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Table 2. Lattice constants and misfits of γ and γ′ phases
Alloy | Point No. | Atomic fraction /% |
---|
Ni | Cr | Al |
---|
Ni75.0Cr25.0 | Point 1 | 74.46 | 25.54 | - | Point 2 | 26.72 | 73.28 | - | Ni75.0Cr18.75Al6.25 | Point 3 | 74.06 | 19.50 | 6.44 | Point 4 | 18.65 | 80.98 | 0.37 | Ni75.0Cr12.5Al12.5 | Point 5 | 74.26 | 13.51 | 12.23 | Point 6 | 14.77 | 82.52 | 2.71 | Ni75.0Cr6.25Al18.75 | Point 7 | 74.18 | 6.96 | 18.86 | Point 8 | 34.27 | 60.22 | 5.51 | Ni75.0Al25.0 | Point 9 | 74.17 | - | 25.83 | Point 10 | 72.79 | - | 27.21 |
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Table 3. Compositions of typical region from as-deposited alloys with different compositions
Alloy | Yield strength /MPa | Compressive strength /MPa |
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Ni75.0Cr25.0 | 231.9 | 752.3 | Ni75.0Cr18.75Al6.25 | 288.8 | 942.9 | Ni75.0Cr12.5Al12.5 | 535.6 | 1264.8 | Ni75.0Cr6.25Al18.75 | 597.3 | 1409.6 | Ni75.0Al25.0 | 601.5 | 1561.6 |
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Table 4. Compressive strength and plasticity of as-deposited alloys with different compositions
Alloy | Initial temperature of vigorous oxidation /℃ | Total mass gain /(mg·cm-2) | Mass gain rate /(mg·cm-2·K-1) |
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Ni75.0Cr25.0 | 700.2 | 0.80 | 5.43×10-3 | Ni75.0Cr18.75Al6.25 | 624.6 | 1.16 | 6.88×10-3 | Ni75.0Cr12.5Al12.5 | 720.6 | 0.68 | 4.77×10-3 | Ni75.0Cr6.25Al18.75 | 750-800 | 0.61 | 4.04×10-3 | Ni75.0Al25.0 | 800-850 | 0.53 | 3.14×10-3 |
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Table 5. Oxidation kinetics data of as-deposited alloys with different compositions
Alloy | Region | Atomic fraction /% |
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O | Ni | Cr | Al |
---|
Ni75.0Cr25.0 | A | 70.30 | 4.77 | 24.93 | - | B | 66.48 | 8.31 | 25.21 | - | Ni75.0Cr18.75Al6.25 | C | 14.06 | 69.28 | 14.09 | 2.57 | D | 67.10 | 1.03 | 26.46 | 5.41 | Ni75.0Cr12.5Al12.5 | E | 7.53 | 78.59 | 10.08 | 3.79 | F | 68.10 | 2.29 | 14.29 | 15.33 | Ni75.0Cr6.25Al18.75 | G | 9.74 | 82.79 | 4.96 | 2.51 | H | 65.50 | 6.64 | 7.70 | 20.16 | Ni75.0Al25.0 | I | 65.75 | 5.44 | - | 28.81 |
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Table 6. Chemical compositions of typical areas taken from oxidized surfaces of as-deposited alloys with different compositions
Alloy | Onset melting temperature /℃ | Offset melting temperature /℃ | Solidification interval /℃ |
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Ni75.0Cr25.0 | 1316.9 | 1362.4 | 45.5 | Ni75.0Cr18.75Al6.25 | 1368.5 | 1400.3 | 31.8 | Ni75.0Cr12.5Al12.5 | 1355.5 | 1393.3 | 37.8 | Ni75.0Cr6.25Al18.75 | 1324.7 | 1371.5 | 46.8 | Ni75.0Al25.0 | 1323.2 | 1376.4 | 53.2 |
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Table 7. Solidification intervals of as-deposited alloys