Internal friction in melt spun Nd60Fe30Al10 magnetic nanostructures

Nanostructured Nd60Fe30Al10magnetic alloys were melt spun at tangential wheel speeds of 5 m/s (V5) and 20 m/s (V20). The damping and the dynamic elastic modulus were measured in an automated sub-resonant forced pendulum in both modes: at fixed frequencies between 0.1 and 1 Hz [150–480 K], and at constant temperature, varying the frequency between 1 × 1 0 − 3 and 10 Hz, always keeping constant excitation. The magnetic properties were characterized by M–H loops and by magnetization vs. temperature measurements in the same temperature range. Ferromagnetic ordering of the Fe-rich phase was observed at 460 and 410 K for samples V5 and V20, respectively. After several thermal cycles between 290 and 150 K virgin samples showed a sharp relaxation peak at 210 K (1 Hz) and a broad one at about 270 K (1 Hz), associated to a para-antiferromagnetic transition in the Nd-rich phase. The high temperature internal friction spectra at 1 Hz show an internal friction peak at T ≥ 500 K. No visible changes in the IF near the Curie temperatures are found, but there are large ‘anomalies’ in the dynamic modulus in the temperature range between the two transition temperatures, that of the Fe-rich μ -like phase and the one of the Nd-rich δ -like phase. These anomalies are significantly affected by the application of a small magnetic field (24 mT) while no changes in the IF are observed.