High-entropy alloys are getting increasingly more attention as potential material candidates for high-temperature applications due to the possibility of including different elements with promising properties with a limited amount of intermetallic phases due to high configurational entropy.

In this work, we study the lightweight $\mathrm{Fe}_{32.3}\mathrm{Cu}_{11.7}\mathrm{Ni}_{10.8}\mathrm{Ti}_{15.9}\mathrm{Al}_{29.3}$ alloy. The microstructure, room-temperature hardness, and oxidation behavior are the scope of our studies. The precipitates after non-isothermal heat treatment were evaluated in terms of fraction, size, and thermodynamic mechanisms of their formation. The significant positive enthalpy in the Fe-Cu subsystem was found to be the main reason for the precipitation reaction. This was verified by analyzing the alloys with variable Fe and Cu content. The morphology transformation from near-spherical to lath-like was found to take place with increasing precipitate size. This morphology transformation was studied in terms of the crystallographic strains. Concerning the oxidation, the building of Ti- and Al-rich oxides was sufficient to prevent drastic oxidation of the alloy. The room-temperature hardness tests were performed to find the optimal size of the precipitates as a dislocation movement obstacle.