Paramagnetic Susceptibilities of Fe and Fe-Si Alloys

Paramagnetic susceptibilities of Fe and Fe-Si alloys (5.75, 6.82, 9.45, 12.65, 14.70, 18.11, 20.85, and 24.38 at. % Si) have been measured up to 1200°C. At high temperatures the paramagnetic susceptibilities of bcc Fe-Si alloys obey the Curie-Weiss law, possibly indicating that the contribution due to s-d exchange interactions is small in comparison with the temperature dependent paramagnetism. The effective Bohr-magneton number of Fe from the high-temperature region is independent of Si content up to about 14 at. % Si. At higher Si concentrations, gradual decrease in the effective Bohr-magneton number occurs. According to the paramagnetic susceptibility measurements, the α-γ transition in iron takes place at 910±3°C. Assuming that the critical temperatures for chemical ordering as given by Glaser and Ivanick are correct, our measurements indicate that the paramagnetic susceptibility, within the experimental error, is not influenced by the destruction of the superlattice above 13 at. % of Si.