Structure and magnetic properties of nanostructured Pr[sub 1-x]Gd[sub x]Co[sub 5] (x=0–1) powders prepared by mechanical alloying.

The phase components, structures, and magnetic properties of Pr[SUB1-x]Gd[SUBx]Co[SUB5] (x = 0 - 1) powders synthesized by mechanical alloying and subsequent annealing have been investigated systematically. The optimal magnetic properties, with a coercivity of 12.5 kOe, a remanence ratio of 0.72, and a maximum energy product of 12.7 MGOe, have been obtained from PrCo[SUB5] powders milled for 5 h and annealed at 700°C for 2 min. The remanence and maximum energy product were decreased monotonically with increasing Gd content, whereas the coercivity was increased, reaching a maximum of 23.7 kOe in Pr[SUB0.2]Gd[SUB0.8]Co[SUB5] powders. X-ray diffraction and transmission electron microscopy observations reveal that an uniform (Pr,Gd) Co[SUB5]/(Pr,Gd)[SUB2]Co[SUB17] nanostructure with an average grain size of 20-30 nm forms in the powders annealing at 700°C. The obtained magnetic hardening apparently originates from the high anisotropy field of the hard (Pr,Gd)Co[SUB5] phase and the uniform nanostructure developed by mechanical alloying and subsequent annealing. [ABSTRACT FROM AUTHOR]