Ordering transformation and magnetic properties of Fe59.75Pt39.5Nb0.75

We have investigated the effect of various heat treatments on the face-centered-cubic-face-centered-tetragonal transformation rate of Fe59.75Pt39.5Nb0.75 bulk alloys. The degree of atomic ordering accompanying this transformation leads to substantial changes in the Curie temperature, which we discuss in terms of a changing number of nearest-neighbor Fe atoms. Additional information on the phase transformation and on the degree of atomic ordering was obtained from the occurrence of the Hopkinson effect and from the c/a ratio and the line width derived from X-ray diffraction. We show that the initial homogenization temperature has a strong influence on the ultimate magnetic properties obtained in a subsequent low-temperature annealing treatment.