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Materials Modeling Tool for Alloy Design to Streamline the Development of High Temperature, High-Entropy Alloys for Advanced Propulsion Systems

Description:

TECHNOLOGY AREA(S): Materials 

OBJECTIVE: Develop a materials modeling tool for alloy design to streamline development of high temperature, high-entropy alloys for advanced propulsion systems. 

DESCRIPTION: The temperature capability of Ni-base superalloy blades has increased by more than 300°C over the last 50 years [Ref 1] and is approaching 1100°C for single crystal superalloys. In spite of many efforts, however, a further improvement in their capability is becoming more difficult due to the low melting point of Ni, which is 1453°C. Considering the ever-increasing demands for materials with higher temperature capabilities to be used in gas turbines with higher efficacy, it is of vital importance to search for alloys based on the concept of High Entropy Alloy (HEA) development. In general, the concept is based on the idea of producing bulk crystalline alloys composed of multiple components being added in proportion that are far beyond their binary solid solubility limits, yet yielding a single-phase solid solution [Refs 1, 2, 3]. In some cases, the solid solutions formed possess simple crystal structures, such as face-centered cubic (FCC) and body-centered cubic (BCC) [Refs 4, 5], and also fulfill the expectations of combining high strength with good ductility [Ref 6]. However, successful efforts with experimental verification have not been reported in the literature. To enable rapid transition of HEAs with higher temperature capability, an innovative modeling tool for high-entropy alloy design that will enable streamlining towards rapid-alloy screening and property-orientation design is needed. This tool must be able to predict the composition of high temperature HEAs for both equiatomic and non-equiatomic formulations for advanced Mo-Si-B alloys. Algorithms should predict microstructural characteristics such as phase evolution, grain size, grain orientation, and microstructural texture. The results of the analysis should be displayed in a graphical way that allows for understanding the new HEAs compositions easily. 

PHASE I: Design, develop and demonstrate the feasibility of algorithms to predict composition of a known high-temperature, high entropy alloy Mo-Si-B. This will include both equiatomic as well as non-equiatomic formulations. Algorithms should include phase evolution, grain size, grain orientation, and microstructural texture. 

PHASE II: Down select to one composition (equiatomic or non-equiatomic) for verification through physical comparison between algorithms developed HEA and non-HEA coupons. Investigation should include the microstructural/structural changes related to various thermal processing, deformation mechanisms (room-temperature and high-temperature creep), and thermal stability/oxidation mechanisms under isothermal and cyclic exposures at elevated temperature for the selected composition. 

PHASE III: Fully develop a materials modeling tool based upon verified algorithms. Demonstrate and validate the modeling tool against existing high temperature alloys. Transition the modeling tool for use in the development of new HEAs for advanced propulsion systems. The technology developed will have applicability to commercial and military aviation manufacturing firms including alloy manufacturers, casting, and forging companies. Private Sector Commercial Potential: The technology developed will have applicability to commercial and military aviation manufacturing firms including alloy manufacturers, casting, and forging companies. 

REFERENCES: 

1: Y. Zhang, T. T. Zuo, Z. Tang, M. C. Gao, K. A. Dahmen, P. K. Liaw, Z. P. Lu (2014). Microstructure and properties of high-entropy alloys, Prog. Mater. Sci. 61, 1-93

2: C. T. Sims, N.S Stoloff, W.C. Hagel (1987). Superalloys II: High Temperature Materials for Aerospace and Industrial Power, Wiley-interscience, USA

3: C. C. Tung, J.W. Yeh, T.T. Shun, S.K. Chen, Y.S. Huang, H.S. Chen (2007). On the elemental effect of AlCoCrCuFeN high-entropy alloy system, Mater. Lett. 61

4: J.-W Yah, S.-J Lin, T.-S Chin, Y.-Y Gan, S.-K. Chen, T.-T Shun, C.-H Tsau, S.-Y Chou (2004). Formation of simple crystal structure in Cu-Co-Ni-Cr Al-Ti-V alloys with multiple metallic elements, Metall. Mater. Trans. A35 (2004) 2533-2536

5: E. Cantor, J. T.H Chang, P. Knight, A. J. B Vincent (2004). Microstructural development in equiatomic multicomponent alloys. Mater. Sci. Eng. A 375-377

6: K. C. Pradep, N. Wanderis, P. Choi, J. Banhart, B. S. Murty, D. Raabe (2013). Atomic scale compositional characterization of a nanocrystalline AlCrCuFeNiZn high-entropy alloy using atom probe tomography, Acta. Mater. 61

 

KEYWORDS: High Entropy Alloy; Modeling; Super Alloys; Gas Turbines; Propulsion Materials; High Temperature Alloy 

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