Improving the Seebeck Coefficient and Electrical Conductivity of Fe₁₁Ti₃Al₆ by Substituting Fe with Cr

In general, any attempt to increase the Seebeck coefficient is usually accompanied by a decrease in the electrical conductivity or vice versa due to the interplay between these two parameters. This work demonstrates that a simultaneous increase in both the Seebeck coefficient and electrical conductivity can be obtained by "doping" in intermetallic alloys. A new alloy composition, Fe₁₀Cr₁Ti₃Al₆, was synthesized by substituting Fe with Cr in Fe₁₁Ti₃Al₆ using mechanical alloying and spark plasma sintering (SPS). The thermoelectric measurements revealed that the Cr substitution led to an increase in the Seebeck coefficient from +27 µV/K in Fe₁₁Ti₃Al₆ to +39 µV/K in Fe₁₀Cr₁Ti₃Al₆, with a corresponding increase in the electrical conductivity from 2.5 × 10⁵ S/m to 4.7 × 10⁵ S/m, resulting in a significant increase in the power factor. The temperature dependence of the thermoelectric properties of this new alloy was also investigated over a temperature range of 50-727°C. The result showed that a maximum power factor of 6.0 × 10^-4 W/m K² was obtained at 53°C.