On the Microstructure and Properties of the Nb-23Ti-5Si-5Al-5Hf-5V-2Cr-2Sn (at.%) Silicide-Based Alloy—RM(Nb)IC
Abstract
:1. Introduction
2. Alloy Design/Selection
3. Experimental
4. Results
4.1. As-Cast (NV1-AC)
4.2. Heat-Treated (NV1-HT)
4.3. Oxidation
4.4. Hardness and Nano Indentation
5. Discussion
5.1. Microstructures
5.2. Oxidation
5.3. Hardness and Nanoindentation
5.4. Comparison with NICE
6. Conclusions
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Acknowledgments
Conflicts of Interest
Appendix A
Alloy | Nb | Ti | Si | Al | Hf | Cr | Mo | Ta | W | Fe | Ge | Sn | Ref. |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
CM1 | 60.5 | 8.3 | 21.1 | - | 0.7 | - | 5.4 | - | 4 | - | - | - | [27] |
EZ1 | 72 | - | 18 | - | 5 | - | - | - | - | - | - | 5 | [28] |
EZ4 | 67 | - | 18 | 5 | 5 | - | - | - | - | - | - | 5 | [28] |
EZ5 | 43 | 24 | 18 | 5 | 5 | - | - | - | - | - | - | 5 | [29] |
EZ7 | 72 | - | 18 | 5 | - | - | - | - | - | - | - | 5 | [28] |
JG2 * | 43 | 24 | 18 | 5 | - | 5 | 5 | - | - | - | - | - | [48] |
JG3 * | 46 | 24 | 18 | 5 | - | 5 | 2 | - | - | - | - | - | [48] |
JG4 * | 41 | 24 | 18 | 5 | 5 | 5 | 2 | - | - | - | - | - | [49] |
JG6 * | 36 | 24 | 18 | 5 | 5 | 5 | 2 | - | - | - | - | 5 | [49] |
KZ2 ** | 46 | 24 | 18 | 4 | - | 8 | - | - | - | - | - | - | [36] |
KZ3 ** | 58 | 24 | 18 | - | - | - | - | - | - | - | - | - | [34] |
KZ4 ** | 53 | 24 | 18 | - | - | 5 | - | - | - | - | - | - | [35] |
KZ5 ** | 48 | 24 | 18 | 5 | - | 5 | - | - | - | - | - | - | [35,36] |
KZ7 ** | 53 | 24 | 18 | 5 | - | - | - | - | - | - | - | - | [35,36] |
MASC | 47 | 25 | 16 | 2 | 8 | 2 | - | - | - | - | - | - | [3] |
NV3 + | 48 | 24 | 18 | - | - | 5 | - | - | - | 5 | - | - | [37] |
NV4 + | 30 | 45 | 15 | - | - | - | - | - | - | 5 | - | 5 | [38] |
NV5 + | 43 | 24 | 18 | - | - | 5 | - | - | - | 5 | - | 5 | [37] |
NV6 + | 53 | 24 | 18 | - | - | - | - | - | - | - | - | 5 | [39] |
NV8 + | 48 | 24 | 18 | - | - | - | - | - | - | 5 | - | 5 | [38] |
NV9 + | 77 | - | 18 | - | - | - | - | - | - | - | - | 5 | [39] |
YG1 | 72 | - | 18 | - | 5 | 5 | - | - | - | - | - | - | [40] |
YG3 | 53 | 24 | 18 | - | 5 | - | - | - | - | - | - | - | [40] |
YG4 | 72 | - | 18 | - | 5 | - | 2 | 3 | - | - | - | - | [25] |
YG5 | 70 | - | 20 | - | 5 | - | - | - | 5 | - | - | - | [26] |
YG6 | 72 | - | 20 | - | - | - | 5 | - | 3 | - | - | - | [26] |
YG8 | 67 | - | 20 | - | 5 | - | 5 | - | 3 | - | - | - | [26] |
ZF4 ++ | 48 | 24 | 18 | - | - | 5 | - | - | - | - | 5 | - | [62] |
ZF5 ++ | 48 | 24 | 18 | 5 | - | - | - | - | - | - | 5 | - | [63] |
ZF6 ++ | 43 | 24 | 18 | 5 | - | 5 | - | - | - | - | 5 | - | [20] |
ZX7 | 46 | 24 | 18 | 5 | - | 5 | - | - | - | - | - | 2 | [14] |
ZX8 | 43 | 24 | 18 | 5 | - | 5 | - | - | - | - | - | 5 | [15] |
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Alloy | Density (g/cm3) | Hardness (HV) | Vol.% Nbss | Vol.% Nb5Si3 |
---|---|---|---|---|
NV1–AC | 7.26–7.43 | 454–503 | 78.5–81.6 | 16.1–19.8 |
7.38 ± 0.1 | 475 ± 17 | 79.6 ± 1.1 | 18.0 ± 1.4 | |
NV1–HT | - | 376–488 | 79.2–83.6 | 15.7–18.1 |
- | 454 ± 35 | 81. 0 ± 1.5 | 16.9 ± 0.9 |
Phases in NV1-AC | Elements | ||||||||
---|---|---|---|---|---|---|---|---|---|
Nb | Ti | Si | Al | Cr | Hf | Sn | V | O | |
Nbss | 56.0–65.3 | 14.4–23.5 | 1.3–2.9 | 4.2–5.5 | 0.3–2.2 | 3.4–4.4 | 1.7–2.5 | 3.3–5.2 | - |
60.6 ± 2.8 | 20.9 ± 1.2 | 2.0 ± 0.4 | 4.9 ± 0.3 | 1.5 ± 0.5 | 3.8 ± 0.3 | 2.1 ± 0.2 | 4.2 ± 0.4 | - | |
Ti-rich Nbss | 40.3–51.9 | 25.5–34.0 | 1.6–2.7 | 5.4–6.1 | 2.0–5.0 | 3.2–4.9 | 2.2–3.0 | 5.2–7.0 | - |
47.5 ± 3.3 | 28.4 ± 2.8 | 2.2 ± 0.4 | 5.7 ± 0.2 | 3.3 ± 0.8 | 4.3 ± 0.5 | 2.8 ± 0.2 | 5.8 ± 0.6 | - | |
Ti, Cr, andV-rich Nbss | 29.8–45.0 | 28.5–35.7 | 1.4–1.7 | 5.1–6.1 | 3.6–8.4 | 4.5–6.0 | 2.4–2.8 | 7.8–10.2 | - |
36.5 ± 3.9 | 32.8 ± 1.7 | 1.6 ± 0.2 | 5.6 ± 0.3 | 6.8 ± 1.1 | 5.3 ± 0.5 | 2.7 ± 0.3 | 8.7 ± 0.8 | - | |
Nb5Si3 | 33.8–36 | 18.8–20.8 | 31.9–33.4 | 3.7–4.1 | 0.2–1.0 | 6.0–7.0 | 0.6–1.0 | 1.2–2.0 | |
34.8 ± 0.9 | 19.3 ± 0.8 | 32.7 ± 0.7 | 3.8 ± 0.2 | 0.5 ± 0.3 | 6.4 ± 0.4 | 0.8 ± 0.1 | 1.7 ± 0.3 | ||
Ti and Hf-rich Nb5Si3 | 14.9–25.3 | 22.4–25.4 | 34.1–35.6 | 3.1–4.4 | 0.2–1.2 | 12.0–17.0 | 0.1–0.5 | 1.4–2.9 | - |
21.6 ± 2.8 | 23.4 ± 1.2 | 34.8 ± 0.5 | 3.6 ± 0.3 | 0.6 ± 0.4 | 13.6 ± 1.2 | 0.3 ± 0.2 | 2.1 ± 0.3 | - | |
Ti-rich Nb5Si3 * | 23.2–36.0 | 18.8–23.0 | 31.9–35.4 | 3.4–4.0 | 0.2–1.0 | 6.0–13.2 | 0.2–0.9 | 1.2–2.6 | - |
29.2 ± 4.8 | 20.7 ± 1.3 | 34.1 ± 1.2 | 3.7 ± 0.2 | 0.4 ± 0.3 | 9.6 ± 2.3 | 0.5 ± 0.3 | 1.8 ± 0.3 | - | |
Lamellar * Nbss + Nb5Si3 | 37.7–40.6 | 21.8–25.1 | 16.6–21.6 | 4.1–4.8 | 0.9–1.8 | 7.2–8.9 | 1.1–1.7 | 2.8–4.1 | - |
39.3 ± 0.5 | 23.2 ± 0.8 | 19.1 ± 1.4 | 4.5 ± 0.2 | 1.3 ± 0.2 | 7.8 ± 0.3 | 1.5 ± 0.2 | 3.3 ± 0.3 | - | |
HfO2 | - | - | - | - | - | 33.4–34.5 | - | - | 65.5–66.6 |
34.0 ± 0.3 | 66.0 ± 0.3 | ||||||||
NV1-HT | |||||||||
Nbss | 54.7–56.4 | 22.8–24.1 | 0.9–1.5 | 5.0–6.1 | 4.5–5.6 | 3.3–4.2 | 2.0–2.8 | 2.0–2.6 | - |
55.6 ± 0.5 | 23.6 ± 0.4 | 1.2 ± 0.2 | 5.6 ± 0.3 | 5.2 ± 0.2 | 3.8 ± 0.3 | 2.6 ± 0.2 | 2.4 ± 0.3 | - | |
Nb5Si3 | 25.1–26.8 | 19.2–20.2 | 35–36.6 | 3.4–4.0 | 1.5–2.2 | 11.8–13.8 | 0.1–0.4 | 0.2–0.6 | - |
25.8 ± 0.5 | 19.6 ± 0.4 | 35.7 ± 0.5 | 3.7 ± 0.2 | 1.6 ± 0.2 | 13.0 ± 0.8 | 0.2 ± 0.1 | 0.4 ± 0.1 | - | |
HfO2 | - | - | - | - | - | 33.0–33.8 | - | - | 66.2–67.0 |
33.5 ± 0.5 | 66.5 ± 0.5 |
Phases Near Surface of NV1-HT | Element | |||||||||
---|---|---|---|---|---|---|---|---|---|---|
N | O | Nb | Ti | Si | Al | Cr | Hf | Sn | V | |
Nbss | - | - | 63.0–63.4 | 18.4–19.6 | 0.1–0.5 | 6.0–6.2 | 2.7–2.9 | - | 2.4–2.5 | 6.0–6.2 |
- | - | 63.2 ± 0.3 | 19.0 ± 0.8 | 0.3 ± 0.2 | 6.1 ± 0.1 | 2.8 ± 0.2 | - | 2.5 ± 0.1 | 6.1 ± 0.1 | |
Nb5Si3 | - | - | 45.9–46.1 | 14.8–15.2 | 33.6–34.0 | 1.8–2.1 | - | 1.2–1.4 | 0.5–0.7 | 1.0–1.3 |
- | - | 46.1 ± 0.1 | 15.0 ± 0.2 | 33.8 ± 0.2 | 2.0 ± 0.1 | - | 1.3 ± 0.2 | 0.6 ± 0.1 | 1.2 ± 0.2 | |
Ti-rich Nb5Si3 | - | - | 32.5–33.5 | 23.3–24.3 | 33.2–33.5 | 3.4–3.8 | 0.4–0.5 | 2.5–3.9 | - | 2.2–2.5 |
- | - | 33 ± 0.4 | 23.9 ± 0.5 | 33.4 ± 0.2 | 3.6 ± 0.2 | 0.4 ± 0.1 | 3.3 ± 0.6 | - | 2.4 ± 0.1 | |
HfO2 | - | 65.6–68.2 | - | - | - | - | - | 31.8–34.4 | - | - |
- | 67.1 ± 1.1 | - | - | - | - | - | 32.9 ± 1.1 | - | - | |
Ti nitride | 34.5–40.9 | - | 2.6–3.4 | 54.8–61.3 | - | - | - | 0.6–1.7 | - | - |
36.9 ± 2.4 | - | 3.0 ± 0.2 | 59.0 ± 2.3 | - | - | - | 1.1 ± 0.4 | - | - |
Alloy | Vol.% Nbss | 700 °C | 800 °C | 900 °C | ||
---|---|---|---|---|---|---|
kl (g·cm−2·s−1) | kp (g2·cm−4·s−1) | kl (g·cm−2·s−1) | kp (g2·cm−4·s−1) | kl (g·cm−2·s−1) | ||
NV1 | 79.6 | - | 3.4·10−11 | - | 2.8·10−10 | 5.4·10−8 (0–16 h), 1.3·10−7 (>16 h) |
NV3 | 28 | - | 1.4·10−11 | 1.4·10−7 | - | 1.4·10−7 |
NV5 | 1.9 | - | 1.3·10−12 | - | 1.3·10−12 | 3.0·10−7 (0–55 h), 1.3·10−7 (>55 h) |
NV6 | 33.5 | - | 1.3·10−11 | 3.3·10−8 | - | 2.1·10−6 (0–17 h), 9.3·10−8 (>17 h) |
NV8 | 15.3 | - | 7.2·10−12 | - | 6.1·10−11 | 3.1·10−7 (0–5 h), 9.8·10−7 (>5 h) |
MASC | 30 | 5.6·10−8 (>10 h) | 6.9·10−12 (0–10 h) | 1.5·10−7 | - | 5.3·10−7 |
Phase | Oxide Scale | ||||||||
---|---|---|---|---|---|---|---|---|---|
Element | |||||||||
Nb | Ti | Si | Al | Cr | Hf | Sn | V | O | |
Nb- and Ti-rich oxide | 18.9–22.3 | 5.2–7.8 | 0.6–0.9 | 1.4–2.0 | 0.2–0.8 | 1.1–1.5 | 0.2–0.9 | 1.0–1.8 | 65.8–68.3 |
19.9 ± 0.7 | 7.0 ± 0.4 | 0.7 ± 0.1 | 1.7 ± 0.2 | 0.5 ± 0.2 | 1.3 ± 0.2 | 0.5 ± 0.2 | 1.3 ± 0.2 | 67.1 ± 0.7 | |
Si-rich oxide | 8.2–9.5 | 6.2–12.0 | 9.2–12.4 | 1.0–1.2 | 3.0–4.3 | 0.2–0.5 | 0.4–0.8 | 64.0–67.4 | |
9.1 ± 0.3 | 7.5 ± 1.1 | 11.4 ± 0.8 | 1.1 ± 0.1 | - | 3.8 ± 0.6 | 0.3 ± 0.1 | 0.6 ± 0.1 | 66.2 ± 0.5 | |
HfO2 | 33.2–33.6 | 66.4–66.8 | |||||||
33.4 ± 0.1 | 66.6 ± 0.1 | ||||||||
Bulk (analyses up to about 300μm below the scale/substrate interface) | |||||||||
Nbss | 28.9–45.5 | 11.5–17.3 | 1.0–1.7 | 2.6–4.1 | 0.7–1.5 | 2.2–3.1 | 1.0–1.8 | 2.0–2.9 | 22.0–47.5 |
36.6 ± 4.2 | 13.1 ± 1.5 | 1.4 ±0.3 | 3.1 ± 0.2 | 1.0 ± 0.2 | 2.4 ±0.2 | 1.4 ± 0.2 | 2.4 ± 0.3 | 38.6 ± 4.5 | |
Ti-rich Nbss | 23.4–39.1 | 14.5–20 | 0.6–1.3 | 2.6–4.0 | 1.6–2.6 | 2.4–3.3 | 1.2–1.8 | 3.1–3.9 | 25.0–48.6 |
29.2 ± 3.9 | 17.0 ± 2.2 | 1.0 ± 0.3 | 3.3 ± 0.5 | 1.9 ± 0.3 | 2.7 ± 0.2 | 1.5 ± 0.2 | 3.5 ± 0.3 | 39.9 ± 5.2 | |
Nb5Si3 | 18.0–26.4 | 18.3–23.2 | 29.2–33.4 | 2.6–4.0 | 0.1–0.6 | 9.3–11.4 | 0.1–0.6 | 1.3–2.2 | 6.7–14.5 |
22.7 ± 3.1 | 20.0 ± 1.5 | 31.5 ± 1.1 | 3.0 ± 0.3 | 0.4 ± 0.1 | 10.5 ± 0.7 | 0.3 ± 0.2 | 1.8 ± 0.3 | 9.8 ± 2.8 | |
Nb5Si3 Oxygen-free | 23.1–29.0 | 20.1–23.0 | 35.1–36.0 | 3.2–3.5 | 0.1–0.7 | 10.2–12.5 | 0.1–0.4 | 1.4–1.9 | |
25.7 ± 2 | 21.7 ± 0.6 | 35.5 ± 0.2 | 3.3 ± 0.1 | 0.4 ± 0.2 | 11.7 ± 0.7 | 0.3 ± 0.1 | 1.6 ± 0.2 | - | |
Lamellar Nbss + Nb5Si3 | 24.5–32.5 | 16.0–19.0 | 10.4–15.1 | 2.9–3.8 | 0.9–1.5 | 4.8–6.3 | 0.9–1.3 | 2.3–2.8 | 24.8–33.3 |
28.4 ± 2.5 | 17.6 ± 1.1 | 12.5 ± 1.9 | 3.3 ± 0.3 | 1.1 ± 0.1 | 5.4 ± 0.5 | 1.1 ± 0.2 | 2.6 ± 0.2 | 28.0 ± 4 | |
HfO2 | 33.4–34.5 | 65.5–66.6 | |||||||
34.0 ± 0.3 | 66.0 ± 0.2 |
Location | Phases | Characteristic Features |
---|---|---|
Oxide scale | Nb- and Ti-rich oxide, Si-rich oxide, and HfO2 | Thickness: non-uniform |
Cracks parallel and transverse to oxide surface | ||
Nbss, and Nb5Si3 “trapped” in scale | ||
Interface between scale and substrate | Sn-rich phase | Very thin discontinuous layer of an Sn-rich phase |
Subscale area | Oxidised Nbss and Nb5Si3 Severe oxidation of Ti-rich Nbss Cracks in Nbss running parallel to interface between scale and substrate Cracked Nb5Si3 | |
Bulk (up to 300 μm below scale) | Nbss, Nb5Si3, lamellar microstructure, and HfO2 | Microstructure architecture same as in as-cast alloy |
Nbss oxidised Ti-rich areas of the Nbss oxidised heavily Nb5Si3 also oxidised but less severely compared with Nbss | ||
In the bulk, some Nb5Si3 grains not oxidised Cracks parallel to the surface formed in Nb5Si3 grains near the Interface between scale and substrate | ||
Partial disintegration (break-up) of lamellar microstructure into Nbss and Nb5Si3 owing to the oxidation of the solid solution |
Condition and Property (GPa) | Average Value for Nb5Si3 | Distance from Nb5Si3 | Average Value for Nbss | ||
---|---|---|---|---|---|
0–5 μm | 5–10 μm | +10 μm | |||
AC—modulus | 230.7 | 144.5 | 136.5 | 138.8 | 139.9 |
HT—modulus | 285.1 | 146.1 | 137.7 | 140.5 | 141.4 |
AC—hardness | 17.02 | 7.1 | 7.0 | 7.0 | 7.04 |
HT—hardness | 20.93 | 7.2 | 6.8 | 6.9 | 6.97 |
Condition | Nbss | Nb5Si3 | ||
---|---|---|---|---|
(GPa) | HV | (GPa) | HV | |
AC | 7.04 | 718 | 17.02 | 1737 |
HT | 6.97 | 711 | 20.93 | 2136 |
Alloy and Condition | Measured * | Calculated + | |||
---|---|---|---|---|---|
A | B | C | D | ||
NV1-AC | 475 | 639.2 | 459.4 | 585.9 | 432 |
NV1-HT | 454 | 670.5 | 480 | 640.8 | 442.5 |
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Vellios, N.; Keating, P.; Tsakiropoulos, P. On the Microstructure and Properties of the Nb-23Ti-5Si-5Al-5Hf-5V-2Cr-2Sn (at.%) Silicide-Based Alloy—RM(Nb)IC. Metals 2021, 11, 1868. https://doi.org/10.3390/met11111868
Vellios N, Keating P, Tsakiropoulos P. On the Microstructure and Properties of the Nb-23Ti-5Si-5Al-5Hf-5V-2Cr-2Sn (at.%) Silicide-Based Alloy—RM(Nb)IC. Metals. 2021; 11(11):1868. https://doi.org/10.3390/met11111868
Chicago/Turabian StyleVellios, Nikos, Paul Keating, and Panos Tsakiropoulos. 2021. "On the Microstructure and Properties of the Nb-23Ti-5Si-5Al-5Hf-5V-2Cr-2Sn (at.%) Silicide-Based Alloy—RM(Nb)IC" Metals 11, no. 11: 1868. https://doi.org/10.3390/met11111868