High entropy alloy on single sub-lattice in MNiSn compound: Stability and thermoelectric properties

Half-Heusler (HH) High entropy alloy (HEA) MNiSn (M=Ti,Zr,Hf) with addition of Al and Sc in the M sub-lattice was studied. The micro-structure of (Ti0.33Zr0.33Hf0.33Al0.005Sc0.005)NiSn compound was examined and its transport properties were measured. The measurements showed the improvement of similar to 40% in the thermoelectric figure of merit in comparison with a similar composition of (Ti0.3Zr0.35Hf0.35)NiSn without Al and Sc. The thermodynamic stability of the alloy was examined using the HEA methodology, including a new proposed HEA parameter for multi-component alloying in only one sub-lattice of the compound. Ab-initio density functional theory (DFT) calculations were carried out to obtain the binary interaction parameters between the components in the sub-lattice of M atoms. The thermodynamic stability of the alloy as a function of the atomic fraction of the elements occupying the same sub-lattice in the compound is analyzed using the new HEA parameter. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

This study investigates the effect of adding Al and Sc in Half-Heusler high entropy alloy, showing a 40% improvement in thermoelectric figure of merit compared to the alloy without Al and Sc. The thermodynamic stability of the compound was examined using HEA methodology and ab-initio density functional theory calculations.