Influence of P substitution for B on the structure and properties of nanocrystalline Fe73.5Si15.5Nb3Cu1B7-xPx alloys

Amorphous ribbons of Fe73.5Si15.5Nb3Cu1B7-xPx (x=0,1,2,3, and 4) have been prepared by rapid cooling on a single copper wheel. The crystallization of α-Fe(Si) phase is independent of the P content in the alloys. Based on Kissinger plots, the activation crystallization energies are determined. The size of the nanoparticles crystallized on an amorphous matrix in heat-treated ribbons is found to be 10-12 nm. The crystallization fraction is determined by using thermal-analysis equipment and we show that after 30 min annealing, this fraction is over 80%. The thermomagnetic curves measured between room temperature and 1000 K revealed clearly two magnetic phases: an amorphous phase at low temperatures and a crystalline one at high temperatures