FORMATION OF R2FE14C COMPOUNDS (R = Y, CE) BY RAPID SOLIDIFICATION

We report formation of the Nd2Fe14B-type compounds Y2Fe14C and Ce2Fe14C via heat treatment of melt-spun ribbons. The existence of several R2Fe14C (R = rare earth) phases has been documented in the literature, but the light R compounds are extremely difficult to prepare by conventional procedures. In particular, the yttrium compound was not found in a study of the equilibrium Y-Fe-C phase diagram, and previously available information on Ce2Fe14C was obtained only by extrapolation of data for Mn-substituted materials. We have prepared the Pr, Nd, Sm, Gd, Dy, Er, and Tm carbides as well, and we analyze the behavior of the Curie temperature through the series using a simple mean-field model. The analysis indicates that the R-Fe exchange interaction energy is significantly smaller for the heavy-R, as compared with the light-R, members of the series.