A cryogenic heat capacity study of the crystallization process in Fe-based nanocrystalline alloys

Thi Mai Hoa Le, Kozo Ishizaki and Mau Chien Dang

Abstract

Nanocrystalline alloys have attracted wide attention because of their excellent soft magnetic properties such as high saturation induction and permeability, low magnetostriction, coercive field and anisotropy. In this paper, the nanocrystalline material is prepared by annealing a melt-spun Fe_73.5Si_13.5Cu₁B₉Nb₃ amorphous ribbon with various annealing conditions. This annealing process produced a series of samples with different crystalline fractions. The primary crystallization stage was investigated by cryogenic heat capacity and x-ray diffraction. The x-ray diffraction results showed that the sample began to crystallize at 490 °C and nanocrystalline Fe₃Si particles were formed in all the annealed samples. The crystalline fraction obtained by the cryogenic heat capacity measurement indicated that the crystalline volume fraction can be controlled by selecting the annealing temperature or annealing time. The crystallization process is almost complete (99.31%) when the sample is annealed at 600 °C for 60 min.