Mechanical alloying and thermoelectric properties of Co doped FeSi2

Mechanical alloying process has been used to produce a Co doped iron-silicide. As-milled powders were of metastable state and fully transformed to β-FeSi₂ phase by subsequent isothermal annealing. Mechanically alloyed powders were successfully consolidated by vacuum hot pressing. As-consolidated iron silicides consisted of untransformed mixture of α-Fe₂Si₅ and ε-FeSi phases. Subsequent isothermal annealing at 830°C in vacuum led to the thermoelectric semiconducting β-FeSi₂ phase transformation. Fraction β-FeSi₂ increased with annealing time and saturated at 100 hours of annealing. Thermoelectric properties of Co doped iron-silicide after isothermal annealing as a function of temperature were investigated from room temperature to 600 K. Transport properties at room temperature were also evaluated in this study.