Observations of multi-phase microstructures in R2(Fe1−xCox)14B where R=Nd or Dy

Abstract Multi-phase microstructures were observed in the psuedo-quaternary phase field of the 2–14–1 magnet materials Nd2Fe14B, Nd2Co14B, Dy2Fe14B, and Dy2Co14B. At equilibrium, (Nd1−yDyy)2(Fe1−xCox)14B had heretofore been widely assumed to be single phase where 1>x>0 and 1>y>0. In this study, three-phase microstructures were observed in (Nd1−yDyy)2(Fe1−xCox)14B when x>0.3 and y>0.5. The Curie temperatures and peritectic decomposition temperatures for Nd2(Fe1−xCox)14B are reported for several values of x in the range 1>x>0.