Relationship between minor hysteresis loops and copper precipitation in Fe-Cu alloys

Abstract

We have analyzed minor hysteresis loops of Fe-Cu alloys with 0.3 wt.% Cu in isothermal aging at 773 K. We found that magnetic coefficients of minor loops show a maximum around the same aging time that Vickers hardness becomes maximum. Both magnetic and mechanical properties are correlated with the microstructure of copper precipitates. These magnetic properties are very useful for nondestructive evaluation of degradation due to neutron irradiation in the nuclear reactor pressure vessels. The minor-loop properties have three advantages compared with coercive force of the major loop in view of their high sensitivity, amount of information, and a small magnetic field to be required for magnetic measurements.