Evaluation of phase stability and diffusion kinetics in novel BCC-structured high entropy alloys

The diffusion kinetics of the BCC-structured high-entropy alloys (HEAs) is studied experimentally for the first time. First, the literature data regarding the transition-metal based, single-phase, BCC-structured HEAs is re-evaluated using the state-of-the-art, HEAs-dedicated TCHEA4 thermodynamic database, signalizing the need for further reassessment of the literature data accumulated during the last decade. The selected Al-Cr-Fe-Mn-V system was used for the interdiffusion experiments. The concentration profiles were evaluated using the numerical combinatorial approach, revealing surprisingly fast diffusion kinetics. The comparison with the available diffusion data for conventional BCC alloys supports recent findings regarding the lack of the 'sluggish diffusion' in HEAs. IMPACT STATEMENT The first-ever experimental study of interdiffusion in BCC-structured high-entropy alloys is conducted, revealing fast diffusion kinetics and providing a further argument against the presence of sluggish diffusion effect in HEAs.