부산대학교 도서관

We show that the temperature dependence of the magnetic losses, measured up to 5 kHz in non-oriented 0.20 mm thick Fe-Si and Fe-Co laminations follows two distinct trends. While the total loss in Fe-Si decreases at all frequencies upon increased temperature, a phenomenon well exploited in electrical machines, a substantial increase is observed in Fe-Co. The moderate softening of Fe-Si with temperature is well understood in terms of decreased anisotropy and increased resistivity, while a further temperature-induced mechanism must be invoked for the opposite behavior of Fe-Co. Such a mechanism is identified with the different thermal expansion coefficients of the coexisting ordered and disordered regions and the ensuing internal strains. These induce local unfavorable anisotropies, chiefly affecting the quasi-static hysteresis and loss.