Dendrite Structure Refinement and Mechanical Property Improvement of a Single-Crystal Superalloy
Abstract
:1. Introduction
2. Materials and Methods
3. Results and Discussion
3.1. As-Cast Microstructure
3.2. Heat-Treated Microstructure
3.3. Stress Rupture Property
4. Conclusions
- Single-crystal rods of types A and B were fabricated under conventional production conditions and with contour-suited insulation measures, respectively. The temperature gradients during the solidification process were measured as 1.9 K/mm and 4.9 K/mm for rod types A and B, and the corresponding dendrite spacings were reduced from 391 μm to 266 μm. This demonstrates the effective role of the contour-suited insulation in refining the dendrite structure.
- The average γ/γ′ eutectic fraction in the as-cast structure of rods A and B was 9.97% and 8.20%, respectively, indicating the effect of dendrite structure refinement on the eutectic reduction in the cast structure.
- After heat treatment, the average residual eutectic fraction in rods A and B was 1.39% and 0.17%, with the latter being only 15% of the former.
- After heat treatment, the average porosity in rods A and B was 0.26% and 0.17%, respectively. Moreover, the number of large porosity holes in rod A was much greater than that in rod B, causing more significant damage to the material’s performance.
- Under the test conditions of 850 °C/650 MPa and 1050 °C/190 MPa, the mean stress rupture lives of rod B were improved by 25% and 5.2%, respectively, compared to rod A. This suggests that the stress rupture life of the superalloy was evidently improved by dendrite structure refinement, especially at medium temperatures.
Author Contributions
Funding
Data Availability Statement
Acknowledgments
Conflicts of Interest
References
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Cr | Co | Mo | W | Re | Al | Ti | Ta | Hf | Ni |
---|---|---|---|---|---|---|---|---|---|
6.44 | 9.57 | 0.61 | 6.38 | 2.94 | 5.60 | 1.02 | 6.47 | 0.11 | Bal. |
Stress rupture properties (h) | Samples | A | Ave. | B | Ave. | ||||
---|---|---|---|---|---|---|---|---|---|
850 °C/650 MPa | 117.3 | 108.5 | 120.0 | 115.3 | 153.1 | 137.0 | 141.8 | 144.0 | |
1050 °C/190 MPa | 86.0 | 88.2 | 93.1 | 89.1 | 99.2 | 94.3 | 87.7 | 93.7 |
Description | Rod A | Rod B | ||||||||
---|---|---|---|---|---|---|---|---|---|---|
Bottom | Middle | Top | Ave. | Bottom | Middle | Top | Ave. | |||
Temperature gradient: G (K/mm) | 1.9 | 4.9 | ||||||||
Dendrite spacing: λ (μm) (Figure 2) | 348 | 374 | 452 | 391 | 287 | 269 | 243 | 266 | ||
As-cast eutectic fraction: fE (%) (Figure 3) | 9.50 | 9.80 | 10.61 | 9.97 | 9.10 | 7.67 | 7.43 | 8.20 | ||
After heat treatment | Residual eutectic fraction | Average: fH (%) (Figure 6) | 1.87 | 1.16 | 1.12 | 1.39 | 0.22 | 0.16 | 0.14 | 0.17 |
Worst: fW (%) (Figure 7) | 4.0 | 4.8 | 5.5 | 4.8 | 1.3 | 1.2 | 1.1 | 1.2 | ||
Micro-porosity ratio ρ(%) | Average: (Figure 10) | 0.28 | 0.26 | 0.23 | 0.27 | 0.22 | 0.15 | 0.13 | 0.17 | |
Worst: (Figure 11) | 0.43 | 0.30 | 0.26 | 0.33 | 0.30 | 0.25 | 0.24 | 0.26 |
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Sun, H.; Ma, D.; Zhao, Y.; Wei, J.; Gong, X.; Sun, Z. Dendrite Structure Refinement and Mechanical Property Improvement of a Single-Crystal Superalloy. Metals 2025, 15, 295. https://doi.org/10.3390/met15030295
Sun H, Ma D, Zhao Y, Wei J, Gong X, Sun Z. Dendrite Structure Refinement and Mechanical Property Improvement of a Single-Crystal Superalloy. Metals. 2025; 15(3):295. https://doi.org/10.3390/met15030295
Chicago/Turabian StyleSun, Hongyuan, Dexin Ma, Yunxing Zhao, Jianhui Wei, Xiaoyi Gong, and Zhongyuan Sun. 2025. "Dendrite Structure Refinement and Mechanical Property Improvement of a Single-Crystal Superalloy" Metals 15, no. 3: 295. https://doi.org/10.3390/met15030295
APA StyleSun, H., Ma, D., Zhao, Y., Wei, J., Gong, X., & Sun, Z. (2025). Dendrite Structure Refinement and Mechanical Property Improvement of a Single-Crystal Superalloy. Metals, 15(3), 295. https://doi.org/10.3390/met15030295