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Experimental investigation of the stability of a new phase in the Al-V-Zr system

Grant number: 18/20443-8
Support type:Scholarships in Brazil - Scientific Initiation
Effective date (Start): November 01, 2018
Effective date (End): March 31, 2020
Field of knowledge:Engineering - Materials and Metallurgical Engineering - Physical Metallurgy
Principal Investigator:Gilberto Carvalho Coelho
Grantee:Vitória de Melo Silveira
Home Institution: Escola de Engenharia de Lorena (EEL). Universidade de São Paulo (USP). Lorena , SP, Brazil

Abstract

The development of new materials with low density and stable mechanical properties at high temperatures is necessary to reduce fuel consumption and gas emissions in the aerospace industry. HEAs (High Entropy Alloys) are a new class of materials that combine elements with high melting point and aluminum and can be candidates for this development. Phase diagrams are a necessary tool for the development and optimization of these alloys, since their microstructures tend to reach thermodynamic equilibrium during use in these applications. High-Entropy Alloys containing Al-Nb-Ti-V-Zr have been studied in our research group. Among the ternary subsystems, one of the least studied is the Al-V-Zr, on which there are only two isothermal sections at 1100°C reported in the literature. In a recent study in our group, a new ternary phase with approximate composition 16Al-33V-52Zr was found in samples in the as-cast state, as well as after heat treatment at 1200°C. Thus, the objective of this work is to investigate the stability of this new ternary phase at different temperatures. Samples will be prepared in an arc furnace using non-consumable tungsten electrode in a water-cooled copper crucible. Heat treatments of the samples will be performed at 1200°C for ten days and at 1100°C for twelve days under vacuum (~10-2 mbar). The microstructures of the samples will be characterized by scanning electron microscopy (SEM), dispersive energy spectroscopy (EDS) and X-ray diffractometry (XRD). The results will allow the determination of the compositional and temperature ranges of stability of the new phase.