Phase diagram of the Fe-rich portion of R-Fe-Al pseudoternary system (R = Dy_(0.65)Tb_(0.25)Pr_(0.1))

摘要

The 1 000℃ isothermal section of the Fe-rich portion of R-Fe-Al (R = Dy_(0.65)Tb_(0.25)Pr_(0.1)) pseudoternary system has been investigated using optical microscopy, X-ray diffraction, EPMA and DTA techniques. The 1 000℃ 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_2Fe_(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(Fe_(1-x)Al_x)_2 is shifted back to the stoichiometric composition when x = 0.15 and remains little changed with 0.15 ≤ x ≤ 0.30. The homogeneity regions of R(Fe_(1-x)Al_x)_3 and R_6(Fe_(1-x)Al_x)_(23) are slightly shifted to the stoichiometric rare earth-rich side with increasing Al content. A vertical section along R = 33.33 atomic percentage is also investigated. It consists of 2 single-phase regions, 4 two-phase regions and 2 three-phase regions.