Energy-efficient synthesis and thermoelectric properties of Ni1-xCrx (x = 0.08, 0.10, and 0.17) alloys

Abstract

Ni1-xCrx alloys are predominantly used as the p-leg in type E and K thermocouples and have promising applications in energy harvesting, including powering low-power devices and deep space power production. Their high electrical conductivity, long-term stability, and cost-effectiveness also make them attractive for spin caloritronic devices due to the modification of the density of states at the Fermi level by Cr impurities. This study introduces an energy-efficient and sustainable approach for manufacturing Ni1-xCrx alloys (with x = 0.08, 0.10, and 0.17) by incorporating KOH as a mineralizer. Nanosized Ni powders, synthesized via hydrothermal methods, are alloyed with commercial Cr powders, promoting rapid diffusion and alloy formation, followed by consolidation at 1110ºC for 6 hours in a 20 % H2 and 80 % N2 atmosphere. Compared to the traditional melting process, which typically takes over 124 hours for alloy formation, our method offers significant time savings. The Ni1-xCrx alloy with x = 0.10 exhibits the highest thermopower, achieves a maximum power factor of 4.56 μW/cm-K2 at 330 K, and exhibits reduced thermal conductivity compared to alloys produced by powder metallurgy. The dimensionless figure of merit (zT) reaches 0.029 at 330 K and 0.022 at 693 K for the Ni0.90Cr0.10 alloy, surpassing values obtained through powder metallurgy.