Phase diagram of the Fe-rich portion of R-Fe-Al pseudoternary system (R = Dy0.65Tb0.25Pr0.1)

The 1000 degrees C isothermal section of the Fe-rich portion of R-Fe-Al (R = Dy0.65Tb0.25Pr0.1) pseudoternary system has been investigated using optical microscopy, X-ray diffraction, EPMA and DTA techniques. The 1000 degrees C isothermal section consists of 9 single-phase regions, 14 two-phase regions and 6 three-phase regions. In the R-Fe pseudobinary system, except the R(2)Fe(17) compound, the homogeneity regions of other compounds are shifted towards the stoichiometric rare earth-rich side. With Fe partially substituted by Al, the homogeneity region of R(Fe1-xAlx)(2) is shifted back to the stoichiometric composition when x = 0.15 and remains little changed with 0.15 less than or equal to x less than or equal to 0.30. The homogeneity regions of R(Fe1-xAlx)(3) and R(6)(Fe1-xAlx)(23) are slightly shifted to the stoichiometric rare earth-rich side with increasing Al content.