DOE ARPA-E, ULTIMATE—Ultrahigh Temperature Materials Program

[Astronuc]

TL;DR Summary

ULTIMATE - Ultrahigh Temperature Impervious Materials Advancing Turbine Efficiency

Ultra-High Temperature Materials Program for development of ultrahigh temperature materials for continuous operation at 1300 ºC (2372 ºF) in a stand-alone material test environment or at 1800 ºC (3272 ºF) with coatings and cooling

WASHINGTON, D.C. – The U.S. Department of Energy today announced $16 million in funding for 17 projects as part of Phase 1 of the Advanced Research Projects Agency-Energy’s (ARPA-E) Ultrahigh Temperature Impervious Materials Advancing Turbine Efficiency (ULTIMATE) program. ULTIMATE teams will develop ultrahigh temperature materials for gas turbine use in the aviation and power generation industries.
https://arpa-e.energy.gov/news-and-...nounces-16-million-funding-phase-1-ultra-high

Project Descriptions - https://arpa-e.energy.gov/sites/def...files/ULTIMATE Project Descriptions_FINAL.pdf

I see some interesting comments/statements in the descriptions. Usually light is not used in reference to refractory alloys. Density of Nb is 8.57g/cm³, Mo 10.2 g/cm³ and Ta 16.6 g/cm³. For comparison, SS316 has a density about 8 g/cm³, Inconel X750 ~8.28 g/cm³, and CMSX-4 ~8.7 g/cm³.

Cannon-Muskegon has develop some high strength alloys for gas combustion turbines, which are used in aircraft engines and aero-derivative gas-fired power turbines. Other groups have developed their own proprietary alloys.

 

[anorlunda]

Thanks for sharing. That could eventually lead to a significant jump in combustion turbine efficiency. That, in turn could shift the competitive balance of using natural gas compared to wind/solar.

No matter what our opinions are about good sources versus bad, economics are still tremendously important.

 

[Astronuc]

I found some articles that cover the evolution of Superalloys at specific times (2004, 2012). I was thinking the CMSX-4 was a later generation, but it is apparently 2nd generation superalloy. Then CMSX-6 and CMSX-10 are perhaps 3rd generation. By 2012, we are up to 6th generation, and perhaps now 7th generation.

Some related PF threads:

High Temperature and Very High Temperature Materials (2022)
https://www.physicsforums.com/threads/high-temperature-and-very-high-temperature-materials.1045301/

Fatigue Failure on Turbine Blade(large subsonic aircraft) (2010)
https://www.physicsforums.com/threa...turbine-blade-large-subsonic-aircraft.376471/

Jet Engine: Turbine Blades and Temperature *2008)
https://www.physicsforums.com/threads/jet-engine-turbine-blades-and-temperature.242166/#post-1781306

Nice introduction and overview of superalloys (2007)
https://www.physicsforums.com/threads/nice-introduction-and-overview-of-superalloys.182039/

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Cannon-Muskegon has a nice list of 89 vacuum melted superalloys. Slide the slider at the bottom to the right to see compositions.
https://www.cannonmuskegon.com/products/vacuum-melt-alloy

Back in 2004, CMSX-4 was the standard. CMSX-6 and CMSX-10 had been introduced and were being evaluated.

NASA Paper from 2004 - NASA/TM—2004-213062 - Joint Development of a Fourth Generation Single Crystal Superalloy, S. Walston, A. Cetel, R. MacKay, K. O’Hara, D. Duhl, and R. Dreshfield (from GE Aircraft Engines, Pratt & Whitney, and NASA Glenn Research Center).
https://ntrs.nasa.gov/api/citations/20050019231/downloads/20050019231.pdf

From the same period (2003)
https://nippon.zaidan.info/seikabutsu/2003/00916/pdf/igtc2003tokyo_ts119.pdf

By 2012 - Development of an Oxidation-Resistant High-Strength Sixth-Generation Single-Crystal Superalloy TMS-238,, by Kyoko Kawagishi, et al.

https://www.researchgate.net/public...-Generation_Single-Crystal_Superalloy_TMS-238
Same paper - https://www.tms.org/superalloys/10.7449/2012/Superalloys_2012_189_195.pdf

From Superalloys 2012 - entire conference available from Wiley.
https://onlinelibrary.wiley.com/doi/10.1002/9781118516430.ch21

A figure shows as creep rupture life was improved (through composition changes), oxidation resistance decreased through the 4th generation (e.g., TMS-138A), then improvements were made in both creep resistance and oxidation resistance (e.g., TMS-196 to TMS-238).
"Figure 6. Graph showing comparisons among alloys in terms of a combination of 1100°C/137 MPa creep and 1100°C oxidation resistances."

From the Kawagishi, et al. paper: "Over the past decade [~2002 through 2012], the addition of Ru has been one of the main subjects of focus to enhance the temperature capability and contribute to the development of new generations of single-crystal superalloys."

Some "4th generation Ni-base superalloys contain 2–3 wt% Ru, which hinders the precipitation of topologically close packed (TCP) phases and improves the high-temperature microstructure stability." Those superalloys "achieved temperature capabilities 30°C higher on average than those of the previous generation superalloys in terms of high-temperature creep strength." Some 5th generation superalloys again optimized composition with increased Ru content to 5–6wt%; "the lattice misfit between the γ and the γ' phases has been controlled to balance the interfacial strengthening and coherency, and the dislocation network at the interface of the γ and the γ' phases has become finer than that of 4th generation superalloys in order to inhibit dislocation migration under stress."

Figure 1 of the Kawagishi, et al. paper shows a plot of a Larson-Miller diagram of creep properties of the investigated alloys.
The 'constant' 20 in the eqaution for LMP is typical of austenitic (fcc) stainless steels as compare to a greater value of about 30 to 33 for certain bcc alloys. I have seen the constant value 16 used for some superalloys. From some work I have done with an austenitic stainless steel at temperatures around 800°C to 930°C, the so-called 'constant' is not necessarily constant, but appears to be alloy (composition) specific, and furthe more, we found indication that the parameter is possibly temperature-dependent, which decreases as temperature increases (there was a lot of scatter in the data, and possibly time at temperature is a factor). This is an area for further, detailed investigation.

In the case of a certain 300 series stainless steel, above about 820°C, carbides start to dissolve, and one will observe a rapid decrease in the elastic modulus, and to a lesser extent the shear modulus, the latter already fairly low compared to the elastic modulus. There are other phase changes as well. So then, could the not-so-constant parameter in the LMP equation be a function of homologous temperature. Normally, one does not operate alloys above 0.8 or 0.85 homologous temperature, but certainly the goal with advanced superalloys has been to raise that limit, if not selecting an alloy with a base element of a higher melting point. However, there reactive elements, Nb, Ta, Hf, Mo, W, Re have poor oxidation resistance, and Hf, Ta, W and Re have much greater densities, which would contribute to higher streses in turbine blades.

Nevertheless, Re can contribute to oxidation resistance of certain thermal barrier coating (TBC) systems.

The role of Re in improving the oxidation-resistance of a Re modified PtAl coating on Mo-rich single crystal superalloy​

https://www.sciencedirect.com/science/article/abs/pii/S1005030220304357