抄録
Based upon thermodynamical theory of a phase transition of the second kind, the effect of pressure on the Curie temperature in the Invar-type iron-platinum alloys with the order-disorder transition has been estimated from the measurements of the temperature dependences of magnetization and magnetostriction. Onset of atomic ordering of the alloys tends to decrease the effect of pressure on the Curie temperature. But, contrary to this tendency, the change of the Curie temperature with pressure in quenched alloys is smaller than the expected value.
The discontinuity ΔCp in the specific heat at the Curie temperature has also been estimated by Landau’s formula. The quantity ΔCp of the disordered state is larger than that of the ordered one. The convenient general expression of the discontinuity in thermal expansion coefficient at the Curie temperature is obtained and on the basis of this expression, it is pointed out that the relation Δθ⁄ΔP=−Cθ⁄Aθ′, which was derived by Belov, is equivalent to Ehrenfest relation.
