Effects of quenching speeds on microstructure and magnetic properties of novel SmCo6.9Hf0.1(CNTs)0.05 melt-spun ribbons

By adding carbon nanotubes (CNTs) to SmCo6.9Hf0.1, novel SmCo6.9Hf0.1(CNTs)0.05 as-cast alloy has been prepared, which consists of Sm(Co,Hf)7 as the main phase, a small amount of SmCo5 and a particle-like grain boundary phase Hf(CNTs). SmCo6.9Hf0.1(CNTs)0.05 ribbons melt-spun at speeds of 10–50 m s−1 have a single TbCu7-type structure. Increasing the quenching speed can result in a decrease in ribbon thickness and grain boundary width. Meanwhile, the grain size tends to be smaller and the grain boundary phase tends to be more dispersed. A new Sm(Co,Hf)7(CNTs)x boundary phase may be formed in SmCo6.9Hf0.1(CNTs)0.05 ribbons. Increasing the quenching speed can also enhance coercivity, remanence and remanence ratio. The ribbons melt-spun at a speed of 50 m s−1 display the best magnetic properties: Hci = 18.781 kOe, Ms2T = 76.87 emu g−1, Mr = 66.79 emu g−1 and Mr/Ms2T = 0.87.