Magnetocrystalline Anisotropy in Quenched and Annealed Fe₃Si

Magnetocrystalline anisotropy constant K 1 of Fe 1- x Si x (0.08≤ x ≤0.25) in both as-quenched and after-annealed samples was determined from torque measurements in 77∼300 K, in order to make clear the difference in K 1 between disorder and order phase (D0 3 type) of Fe 3 Si at x =0.25. The difference in K 1 between both the cases began to appear at x ≃0.17, and values of K 1 for x =0.25 were determined to be - 1.01× and 0.94×10 5 erg/cm 3 at 77 K in the as-quenched and the after-annealed, respectively. This difference in K 1 was apparently due to the one in the degree of order in D0 3 ; the former value was thought to be of nearly perfect disorder in long range and the latter of perfect order. In any case, it was concluded that K 1 of Fe 3 Si is negative in disorder and positive in order (D0 3 ).