Preparation of Fe_0.95Co_0.05Si₂ Material by Mechanical Alloying and Its Thermoelectric Properties

N-type β-FeSi2 thermoelectric material Fe0.95Co0.05Si2 deped with Co was prepared by mechanical alloying and vacuum sintering.XRD and SEM were applied to analyze the phase composition and microstructure of the material,and the powders prepared by mechanical alloying were analyzed by DSC.The thermoelectric properties of the sintered samples were tested.The results show that the mixed powders of Fe,Co and Si had been fully alloyed after milling for 3 h.The formed phases were alloy phases composed of β-FeSi2,α-Fe2Si5 and ε-FeSi.With the extension of milling time,alloy powders became more homogeneous and smaller,and the content of β-FeSi2 gradually increased.However,a single-phase β-FeSi2 could be obtained by mechanical alloying for 20 h and sintering at 1 373 K for 2 h and 1 073 K for 2 h.The alloy powders began to decompose at 1 177 K.With the increase of temperature,Seebeck coefficient α and electric conductivity σ of the Fe0.95Co0.05Si2 sample increased while thermal conductivity к decreased,which led to the maximum dimensionless thermoelectric figure merit of 0.11 was obtained at 773 K.