Effect of ${\rm D}0_{3}$ Ordered Phase on Total Loss of 6.5 wt% Grain-Oriented Silicon Steel

B2 and D0₃ antiphase domains are known to increase the total loss of high silicon steels due to the hindrance of magnetic domain movement. In order to investigate a detailed effect of the ordered phases on total loss behaviors, 6.5 wt% grain-oriented silicon steels were fabricated by the diffusion of SiO₂ textiles and annealed at 600^° with different annealing time. With increasing the annealing time, the average sizes of the antiphase domains increased and moreover the boundary character of D0₃ antiphase changed from 1/4〈111〉 to 1/2〈100〉. These new boundaries were observed to be anisotropically grown and to increase a lancet domain density. And this increase of the lancet domains density led to increase the total loss because these new boundaries introduced additional strain to the matrix. These results suggest that the formation of the D0₃ -type 1/2〈100〉 antiphase boundaries should be controlled to reduce the total loss of high silicon steels.