High-entropy alloys (HEAs) have attracted considerable attention due to their unique properties, such as high strength, hardness, and corrosion resistance. In particular, the equiatomic Al-Cu-Fe-Ni-Ti alloy is of interest due to the possibility of forming a B2 phase in it, which has an ordered structure.
The study of the B2 phase formation in this alloy was carried out using differential scanning calorimetry (DSC) and X-ray diffraction (XRD) methods. The DSC results showed the presence of an exothermic peak corresponding to the ordering process and the formation of the B2 phase. XRD analysis confirmed the formation of the B2 phase after annealing the alloy at a certain temperature.
The stability of the B2 phase was assessed by long-term annealing at different temperatures. It was found that the B2 phase remains stable up to a certain temperature, after which it decomposes into other phases. This decomposition may be associated with diffusion processes and the system’s tendency to minimize energy.
The study showed the possibility of forming the B2 phase in the equiatomic Al-Cu-Fe-Ni-Ti HEA. The stability of this phase depends on the annealing temperature and can be a determining factor for the mechanical properties of the alloy. Further studies are aimed at optimizing the heat treatment to obtain a single-phase B2 structure with improved characteristics.
In this work, a single-phase high-entropy Al-Cu-Fe-Ni-Ti alloy was prepared by melting pure metals in an induction furnace with radio-frequency heating under argon atmosphere. The obtained alloy demonstrated the formation of an ordered B2 structure with a lattice parameter of 0.289 nm. The stability of the structure of this single-phase high-entropy alloy to mechanical stress was studied by high-energy ball milling. Milling was carried out at 400 rpm for 10, 20 and 40 h in hexane medium with a grinding media to powder mass ratio of 40:1. After 40 h of mechanical milling, the formation of a nanocrystalline structure (with a grain size of about 10 nm) consisting of a face-centered cubic (FCC) phase (disordered B2) was detected, which was confirmed by X-ray diffraction and transmission electron microscopy. The structure of the equiatomic high-entropy Al-Cu-Fe-Ni-Ti alloy turned out to be quite resistant to mechanical milling for 40 hours, while with an increase in milling time, only a decrease in grain size and an increase in crystal lattice deformations were observed.
Author: Yogesh Kumar Yadav, Mohammad Abu Shaz, Nilay Krishna Mukhopadhyay, Thakur Prasad Yadav
Institute:
Department of Physics, Institute of Sciences, Banyaras Hindu University, Varanasi, Uttar Pradesh 221005, India
Department of Metallurgical Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005, India
Department of Physics, Faculty of Science, Allahabad University, Prayagraj, Uttar Pradesh 211002, India