Conduction type evolution during eutectoid decomposition of Mn-added α-Fe2Si5 alloy

An n-type conduction of the Mn-doped β-FeSi2 phase was observed in the isothermal annealing of the α-Fe2Si5 based alloy. Investigations of microstructures and transport properties proved that n-type conduction is caused by the abundant Fe vacancies in the supersaturated β-FeSi2(Si) solution, which exists as an intermediate state in the eutectoid decomposition, α-Fe2Si5 → β-FeSi2 + Si.