Effects of quenching speeds on microstructure and magnetic properties of novel SmCo 6.9Hf 0.1(CNTs) 0.05 melt-spun ribbons

Abstract

By adding carbon nanotubes (CNTs) to SmCo 6.9Hf 0.1, novel SmCo 6.9Hf 0.1(CNTs) 0.05 as-cast alloy has been prepared, which consists of Sm(Co,Hf) 7 as the main phase, a small amount of SmCo 5 and a particle-like grain boundary phase Hf(CNTs). SmCo 6.9Hf 0.1(CNTs) 0.05 ribbons melt-spun at speeds of 10–50 m s −1 have a single TbCu 7-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 SmCo 6.9Hf 0.1(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: H ci = 18.781 kOe, M s2T = 76.87 emu g −1, M r = 66.79 emu g −1 and M r/ M s2T = 0.87.