EUROPEAN INTERCOMPARISON OF MEASUREMENTS ON PERMANENT-MAGNETS

This report presents the results of a European intercomparison of meas urements on permanent magnetic materials. The intercomparison consiste d of two parts, namely (A) measurements on cylindrical specimens of Al NiCo and NdFeB in a closed magnetic circuit; (B) measurements on spher ical specimens of NdFeB in an open magnetic circuit using vibrating sa mple or SQUID magnetometers. A total of 24 laboratories took part in t he intercomparisons. Together with the other specimens, nickel referen ce specimens were circulated for calibration purposes. The results of the intercomparisons are complex, but in general the agreement obtaine d was quite good. A comparison of the two parts shows that the differe nce B(r) is relatively small, where the differences in H(c), H(cb), an d (B-H)max. are considerable, which can be interpreted in the light of the aging of the NdFeB spherical specimens due to the preparation pro cess.