Experimental study and thermodynamic modeling of the Al-Nb-Ta system

• Grant number: 23/18091-4
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: April 01, 2024
• End date: March 31, 2028
• Field of knowledge: Engineering - Materials and Metallurgical Engineering - Physical Metallurgy
• Principal Investigator: Gilberto Carvalho Coelho
• Grantee: Caio Simão de Barros
• Host Institution: Escola de Engenharia de Lorena (EEL). Universidade de São Paulo (USP). Lorena , SP, Brazil

Abstract

High Entropy Alloys containing Al and refractory metals are promising structural materials for aeronautical applications, complementary to Ni-based superalloys, both for their performance at high temperatures and for their low specific mass and, therefore, interesting specific properties. The development of this type of alloys depends, among other aspects, on the construction and maintenance of thermodynamic databases and, therefore, on the experimental study of simpler order systems - such as binary and ternary - and the extrapolation of these to higher order systems, with 5 or more elements. One of the subclasses of HEAs of interest are those containing Al and high melting point metals. In this scope, our research group has studied binary and ternary systems of the Al-Cr-Nb-Ta-Ti-V-Zr multicomponent system. Among these systems, one of which little information is available in the literature is the ternary Al-Nb-Ta. Thus, knowledge about the phase relationships of this system corresponds to an important contribution to the development of HEAs, especially for work linked to the development of databases. The present project aims to add new information to the literature about the liquidus projection, isothermal section at 1000 and 1200 °C and thermodynamic modeling of the Al-Nb-Ta system. The experimental investigation will be carried out through arc-melted samples, equilibrium heat treatments at 1000 and 1200 °C, microstructural characterization using electron microscopy (SEM), electron microanalysis (EDS) and X-ray diffractometry (XRD). The results will allow more precise knowledge of the phase relationships in this system, as well as being used to feed the thermodynamic modeling process, following the Calphad protocol.