The microstructure and magnetic properties of FeCo alloys with different OH¯/(Co2+, Fe2+) ratio and annealing temperature

The OH¯/(Co2+, Fe2+) ratio and annealing temperature (Ta) have a great influence on the microstructure and magnetic properties of FeCo alloys. In this work, the OH¯/(Co2+, Fe2+) ratio was first changed from 10:1 to 30:1. When the OH¯/(Co2+, Fe2+) ratio was 20:1, pure FeCo powder samples were obtained. After annealing at 400 °C, the saturation magnetization (Ms), remnant magnetization (Mr), and coercivity (Hc) were 155 emu/g, 15 emu/g, and 210 Oe, respectively. Then the prepared FeCo samples were annealed in the range of 300 °C–600 °C for 5 h. With the increasing of Ta, the better magnetic properties of FeCo powders were observed. When the Ta was 600 °C, the Ms, Mr, and Hc were 202 emu/g, 12 emu/g, and 87 Oe, respectively. When the OH¯/(Co2+, Fe2+) = 20:1 and Ta was 400 °C, the real part of complex permittivity was between 8.2 and 9.5, and the corresponding imaginary part was between − 0.3 and 1.3. Furthermore, the maximum reflection loss (RL) value of FeCo powders (20–30 nm) was − 35.49 dB which showed great potential in corresponding industrial applications.