Structure, processing and properties of advanced multicomponent alloys for biomedical and energy storage applications

Abstract

Multicomponent alloys such as high entropy alloys have attracted a lot of attention due to their remarkable set of attractive functional properties. These alloys may have excellent mechanical and corrosion properties in addition to high biocompatibility for applications as biomaterials, or even exhibit competitive hydrogen storage properties for applications as metal hydrides with high gravimetric capacity operating at room temperature. It's mainly due to the vast compositional field existing in multicomponent alloys, since such properties are extremely sensitive to the compositional changes, and therefore, it is possible to find alloys with optimized properties for each of these applications. This research proposal aims to investigate the structure, processing and properties of new multicomponent alloys for advanced applications such as biomaterials and metal hydrides. For applications as biomaterials, our main interest relies on the searching for multicomponent alloys with a single phase containing the body centered cubic (BCC) structure belonging to the alloys systems not explored in the literature: (TiZrNbTa)1-XSnX and (TiZrNbMo)1-XSnX where X = 0, 0.1, 0.15 e 0.2 at%. While for the applications involving metal hydrides, our main interest relies on the searching for multicomponent alloys with a single phase containing the hexagonal C14 laves phase belonging to the systems: AB, AB2, A1,5B and AB1,2 (where A represents the elements with the highest affinity to absorb hydrogen, such as: Ti, Zr, Nb and V; while elements with low affinity for hydrogen, such as: Fe, Cr, Mn, Ni, Co). For each specific application, the multicomponent alloys will be properly selected based on thermodynamic calculations by employed empirical parameters and by thermodynamic simulation using the CALPHAD method (Thermocalc Software) and subsequently prepared in a controlled atmosphere arc melting furnace. After preparation of samples, the aim is to investigate the effects on mechanical properties, biocompatibility and hydrogen storage properties resulting from microstructural changes caused by the use of two types of processing: i) heat treatments at controlled temperature; ii) severe plastic deformation using the HPT (High-Pressure Torsion) technique. Finally, it is expected that this research project will contribute to the increase in the use of multicomponent alloys in applications such as biomaterial and as metal hydride in various industrial sectors, and in particular, enable the training of human resources capable of promoting the advancement of science in disruptive technologies, such as multicomponent alloys. (AU)