Magnetic hysteresis properties of nanocrystalline (Nd,Ho)-(Fe,Co)-B alloy after melt spinning, severe plastic deformation and subsequent heat treatment

• Multistage treatment of high coercive (Nd0.55Ho0.45)2.7(Fe0.8Co0.2)14B1.2 alloy.
• Melt spinning, SPD and heat treatment increase the magnetic energy product.
• Modelling the magnetic properties within the framework of Stoner-Wohlfarth theory.

A study is made of the effect of multistage treatment on the magnetic hysteresis properties at room temperature and below of high coercive (Nd0.55Ho0.45)2.7(Fe0.8Co0.2)14B1.2 alloy including melt spinning (MS), severe plastic deformation (SPD) and heat treatment (HT). It is shown that SPD and HT of MS samples improves the rectangularity of the second quadrant part of the hysteresis loop resulting in a more than 25% increase of the maximal magnetic energy product as compared to ordinary MS processing. The observed changes in the magnetic properties of the samples are discussed and modelled within the framework of Stoner-Wohlfarth theory of magnetization reversal processes in uniaxial ferromagnets.