The Fe2VAl Heusler alloy was reported to have good thermoelectric properties.
Because the natural resource of vanadium is insufficient, Fe2TiAl based alloys
were studied. Ni, Co, or Cr was substituted to stabilize the Heusler structure
and to control the valence electrons. The Seebeck coefficients decreased in the
Heusler single-phase region when these fourth elements were added, probably
because the Fermi level was lying above the minimum in the density of state. The
maximum and minimum Seebeck coefficients were +50 microV/K in Fe2(Ti0.6Cr0.4)Al
and ¡-34 microV/K in (Fe0.2Co0.8)2TiAl, respectively. Their electric
conductivities were metallic judged by their temperature dependency. The
characteristic semiconducting behavior of the Fe2VAl Heusler alloy due to a
pseudo gap in the density of state was not observed in the substituted Fe2TiAl
alloys.