Anomalous Concentration Dependence of Thermoelectric Power of Fe–Ni (fcc) Alloys at High Temperatures

The thermoelectric power of Fe–Ni alloys relative to Pt was measured up to 1050°C in the whole range of concentration. Great care was given to the phase transition of the alloys. The concentration dependence of thermoelectric power in the fcc phase at high temperatures shows a distinct anomaly around 50 at% Ni, suggesting that the alloys have the tendency to separation into two fcc phases. The so-called Invar problem is considered to be closely related to this anomaly.