材料期刊网

The structure, phase transformation and magnetic properties of mechanically alloyed (MA) alloys Nd16Fe76-mCm (7 less than or equal to m less than or equal to 11) and Nd16Fe84-mCm-yBy (0 less than or equal to y less than or equal to m, m = 7, 8, 9) have been studied systematically. The Nd2Fe14C compound can be formed within a wide window for the range of composition and annealing temperature. More carbon than the stoichiometric content for Nd2Fe14C is necessary to stabilize the tetragonal structure. Substitution of boron for carbon can accelerate the phase transformation from Nd2Fe17Cx to Nd2Fe14(C, B) and increase the magnetic properties drastically. There is an fee structure Nd-rich phase in the mechanically alloyed Nd-FeC alloy. The lattice constant of the Nd-rich phase decreases as the boron content increases. Nd2Fe14(C, B) compounds formed in the alloys with same boron content and different carbon contents have different Curie temperatures. The Curie temperatures also vary with the variation of annealing temperature. The best magnetic properties achieved in Nd16Fe76B5C3 alloy are H-i(c) = 1480 kA m(-1), M(r) = 0.71 T and(BH)(max) = 91.5 kJ m(-3).