抄録
Reversible temperature coefficients of magnetic flux densities at various operating points on the demagnetization curves of columnar Alnico 5, columnar Alnico 8 and Fe-Cr-Co alloy magnets were measured using a nuclear magnetic resonance method. The temperature coefficient of Alnico 5 is-(2.0±0.3)×10−4/°C between −20 and 50°C, of which the absolute value has a tendency to decrease slightly with decreasing permeance. For Alnico 8 and Fe-Cr-Co alloy, however, the temperature coefficients strongly depend on their operating points, and they markedly decrease with decreasing permeance, until the sign of temperature coefficient changes from negative to positive at some operating points near the knees of their demagnetization curves. It is found that for Alnico 8 the coefficient strongly depends on the aging condition also.
The temperature effects are reasonably explained by an offset effect of the magnetization between the weakly ferromagnetic matrix and strongly ferromagnetic precipitates in the spinodal decomposed magnet alloys, which can be expected to vary with their operating points as well as with the aging condition.
