Structural and magnetic properties of Nd-Fe-Cu-B melt spun ribbons

Alloys with nominal compositions x[Nd2Fe14B] + (2-x)[Nd70Cu30], x= 10, 50, and 75 % wt., were synthesized by melt spinning at low wheel speeds. Phase constitution and magnetic properties were preliminary investigated by XRD, TMA and magnetization measurements. As-spun samples were partially crystallized. In as-spun samples with x= 10 % wt. a metastable phase, referred as delta*, with T-C= 192 degreesC and iHc= 4.77 kOe was formed. Very high coercivities were measured in as-spun and annealed samples with x= 50 % wt. and 75 % wt.. This is attributed to the formation of Nd2Fe14B hard particles. A reduction of the Curie temperature of this phase was also measured.