The Heisenberg ferromagnet model has been studied theoretically using the Weiss mean-field theory and Green’s function technique. The equations for the Curie temperature, magnetization, and magnetic susceptibility were analytically derived. Moreover, we proved, that our results are useful in description of real materials. The calculated value of Curie temperature for [Formula: see text] alloy correspond well with the experimental results obtained recently on the base of the temperature dependences of magnetization.