The phase transformation of NdFeB melt-spun alloys with low Nd content of 4–8 at. % was investigated by thermomagnetic analysis and x-ray diffractometry. Experimental results have shown that the metastable Nd2Fe23B3 compound formed in the alloys is considered to be transformed to Nd2Fe23B3+α-Fe+Fe3B in the temperature range of 550–690 °C, α-Fe+Fe3B+Nd1+eFe4B4 in the temperature range of 690–730 °C and finally α-Fe+Nd1+eFe4B4 above 840 °C. From the results, it has been concluded that Nd2Fe14B is not formed from metastable Nd2Fe23B3. On the other hand, the melt-spun alloy of Nd2Fe23B3 (∼Nd7.1Fe82.1B10.7) annealed under optimum conditions has been found to be composed of α-Fe, Fe3B, and Nd2Fe14B phases. The alloy has a coercivity comparable to Fe3B-based Nd4Fe77B19 and relatively high-energy product of about 71.6 kJ/m3 (∼9 MG Oe).

Effects of mechanical machining on the magnetic properties of small NdFeB magnets were investigated by pulsed field magnetometry. Unlike the large sample, the small magnets machined by spark wiring, diamond cutting and hand grinding showed a kink on the second quadrant of demagnetization curves. The breaking samples resulted in no kink because the cleavage fracture characteristics along grain boundary conserves the Nd 2 Fe 14 B grains from mechanical damage. Annealing the machined samples at 200 and 300 °C recovered coercivity to some extent, and the elimination of machined surface by chemical etching increased remanence and squareness of demagnetization curve. However, the kink on demagnetzation curve did not disappear by annealing and chemical etching.

A pulsed field magnetometer with maximum field of 8 MA/m has been constructed by applying 3 axis compensation and analog integration techniques. The m-coil homogeneity, calibration, measurement sensitivity and sample loading problem have been examined. Using the magnetometer full magnetic characterisation of a small sized NdFeB magnet was performed satisfactorily.

An inductive magnetometer is described for measurements using the pulsed magnetic fields up to 10 T at room temperature. The sensing element of the magnetometer is a modification of a three-axis-compensated design. A distinctive feature of the magnetometer described is the independent compensation of signals induced by each of the spatial components of the pulsed magnetic field. Sensitivity of the magnetometer is 5×10−4 emu and is limited mainly by irreproducibility of the magnetometer compensation (10−6 of the signal from the working coil with an inner diameter of 4 mm). The magnetometer demonstrates high sensitivity for volume magnetization and magnetic susceptibility measurements (10−2 emu/cm3 and 10−7, accordingly, for samples with a volume of 60 mm3). As examples, the magnetization curves of some hard magnetics (bulk and thin films) and common diamagnetic materials are measured.