Effect of heat treatment time on magnetic properties of NdFeB-based permanent magnetic alloys

Abstract

In our current study, NdFeB-based permanent magnet ribbon alloys were produced by using melt spinning method, which is one of the rapid solidification methods and very common in the production of ribbon-shaped, amorphous and/or semi-crystalline alloys. During the production of each NdFeB alloy, 15 wt.% of waste magnet was included in the composition of the alloys. The produced permanent magnet alloys were heat treated for 5 and 10 minutes by using a heat treatment temperature of 710 °C and very high heating and cooling rates of 285 K/s. The effect of the heat treatment time applied at the same temperature on the magnetic properties of the strip alloys was investigated. While the increase in heat treatment time resulted in a remarkable change in magnetic coercivity and maximum energy product properties, there was not much change in the properties such as saturation magnetization and magnetic remenance. As clearly seen, increasing heat treatment time resulted in a continuous decrease in magnetic coercivity from 5030.5 Oe to 2279.4 Oe, maximum energy product first showed a dramatic increase from 62.02 kJ/m3 to 103.73 kJ/m3, and then a dramatic decrease to 38.63 kJ/m3, indicating a decrease in the permanent magnetism of the alloy.