Temperature Dependence of Lancet Domains in Grain-Oriented Fe-3%Si Steels

The change in the lancet domains of grain-oriented steels in the range from the room temperature (RT) to far above the Curie temperature (T_c) was investigated using the domain observations by the photoemission electron microscopy combined with X-ray magnetic circular dichroism and the domain theory. Lancet domains were observed to be annihilated at the temperature below T_c, with 180° basic domains occurring. The minimization of the magnetic free energy considering the intrinsic physical constants as the functions of the temperature enabled us to quantitatively explain the observed temperature dependence of lancet domains. The present model revealed that the temperature dependence of the cubic anisotropic constant greatly contributes to the annihilation of lancet domains at the temperature below T_c. The improvement of the crystal misorientation, the thinner thickness, and the enhancement of the tensile stress applied to the steels are predicted to reduce the annihilation temperature of lancet domains. The tensile stress required to annihilate lancet domains at 200 °C is predicted to allow approximately half the stress to annihilate them at RT.