Production and Characterization of Samples with Compositional Gradients of Precipitation-Hardened High-Entropy Alloys.

• Grant number: 24/18868-1
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate (Direct)
• Start date: September 01, 2025
• End date: August 31, 2026
• Field of knowledge: Engineering - Materials and Metallurgical Engineering - Physical Metallurgy
• Principal Investigator: Francisco Gil Coury
• Grantee: João Henrique Schiavon Mota
• Supervisor: Yannick Champion
• Host Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil
• Institution abroad: Université Grenoble Alpes (UGA), France
• Associated to the scholarship: 23/09668-6 - Production and characterization of samples with compositional gradients of precipitation-hardened high-entropy alloys, BP.DD

Abstract

In 2004, a new class of metallic alloys was introduced: High Entropy Alloys (HEAs). These alloys are defined by their composition, containing multiple principal elements, where each constituent can be considered a solute. The thermodynamic equilibrium of this alloy family is attributed to an increase in configurational entropy, which stabilizes a single-phase alloy. During their development, alloys with precipitates showed an additional contribution to strength due to precipitation-hardening. For HEAs containing Ni, Al, Ti, and Nb, the L12 precipitate plays a crucial role in strengthening. Typically coherent with the FCC matrix, this type of precipitate ensures high strength in nickel-based superalloys. Given the vast compositional space of HEAs, designing an alloy with an optimal precipitate fraction is a significant challenge. Computational tools can assist in this process, but they are heavily reliant on their databases. To develop a robust database for computational approaches and alloy design, this project proposes an experimental high-throughput system for the creation and characterization of HEAs containing L12 precipitates. Compositional gradient samples will be produced using diffusion couples, and their mechanical characterization will be carried out through nano-indentation. This technique allows for the assessment of hardness in specific compositions within the sample, which contain varying fractions of precipitates. To extract maximum information from the nano-indentation curves, a theoretical study based on mechanical metallurgy and continuum mechanics will be conducted. Additionally, XRD, SEM, TEM, and APT techniques will be employed to correlate this evaluation with local composition and phase fraction. The project's outcome will provide a comprehensive database linking composition, phase fraction, and mechanical properties, supporting computational methods and facilitating alloy design.