High temperature in-situ observations of magnetic domains in Fe-Co alloys

Abstract

In-situ observations of magnetic domain structure in Fe-Co alloys with Co concentrations of 4.6 ∼ 50 at% were made by the optical Kerr microscopy in the temperature range from R.T. to the Curie temperature (1103 K ∼ 1253 K). The magnetic domain structures could be successively observed up to the Curie temperature (1103 K ∼ 1253 K) and the average domain which was found to increase with increasing temperature. The contrast of magnetic domains in an Fe-4.6 at%Co alloy gradually decreased with increasing temperature and disappeared near the Curie temperature (1103 K). On the other hand, the magnetic domain structure in an Fe-50 at%Co alloy could be clearly observed at immediately below the α/γ phase transformation temperature (1253 K). Furthermore, it was found that the magnetic domain walls tended to orient perpendicularly to the α/γ interphase boundaries in an Fe-50 at%Co alloy at the α/γ phase transformation temperature.