Research Projects

The proposed research focuses on utilizing a computational alloy design approach to develop advanced refractory multi-component alloys (RMCAs) for high-temperature structural applications (≥ 1300°C). These are being proposed as alternatives to traditional Ni-based superalloys, which are currently limited by their melting points and thermal properties. The rationale stems from the urgent need to enhance energy conversion efficiency and reduce CO₂ emissions in the energy and transport sectors, where materials capable of operating above 1200°C are critical. While Ni-based superalloys offer excellent performance up to ~ 1100°C, further advancements are constrained by their fundamental properties. Refractory metal-based alloys, particularly those based on Cr, Mo, and Nb, exhibit higher melting points and superior high-temperature strength but are hampered by poor oxidation resistance and low ductility. Recent findings suggest that controlled additions of Al and Si can significantly improve oxidation resistance by promoting the formation of stable, protective oxide layers (Al₂O₃ and SiO₂), which remain effective at temperatures exceeding 1100°C. However, current alloy development in this space is largely empirical, requiring extensive experimentation and lacking a robust theoretical framework. The scientific objective of this project is to implement a CALPHAD–DFT–based computational alloy design strategy to systematically develop and optimize Cr-Nb/Mo-Al/Si RMCAs with tailored phase constitution and enhanced high-temperature performance. The central hypothesis is that a computationally guided approach, underpinned by a reliable and experimentally validated thermodynamic database for the Cr–Mo/Nb–Al/Si system, will enable the prediction and realization of single-phase or two-phase microstructures with optimal oxidation resistance, hot corrosion resistance, mechanical strength, and ductility. The methodology will involve: (1) thermodynamic modeling and CALPHAD-DFT calculations to identify promising alloy compositions and phase equilibria in Cr-Nb/Mo-Al/Si systems; (2) synthesis of selected alloys via vacuum arc melting, ensuring chemical homogeneity and minimal contamination; (3) comprehensive microstructural and phase characterization using advanced techniques such as XRD, SEM-EDS/EBSD, EPMA, TEM, and APT; and (4) evaluation of high-temperature oxidation, hot corrosion resistance, and mechanical properties including creep and ductility under service-relevant conditions. The significance of this research lies in its potential to bridge critical knowledge gaps by establishing a reliable thermodynamic database, identifying the mechanisms governing phase stability and oxide formation, and providing a predictive framework for alloy design. If successful, the project will not only advance fundamental understanding of phase equilibria and oxidation mechanisms in complex refractory systems but also deliver practical high-performance materials for next-generation energy, aerospace, and industrial applications, thereby contributing to improved efficiency, reduced emissions, and enhanced sustainability in key sectors.