Experimental investigation and thermodynamic description of the Fe−Nd−Pr system

Abstract

The microstructures, crystal constitutions and phase transformation temperatures of the Fe−Nd−Pr alloys were examined by the scanning electron microscopy equipped with energy dispersive spectrometer, X-Ray diffraction and differential thermal analyzer, respectively. The liquidus surface projection, the isothermal sections at 873 and 673 K, and the partial isothermal section at 933 K within 0∼40 at.% Pr and 0∼80 at.% Fe of the Fe−Nd−Pr system were constructed. Especially, the primary solidification region of Fe17Nd5 was determined by thermal analysis during the heating process of the annealed alloys, since it is hard for Fe17Nd5 to crystallize directly from liquid while the precipitated Fe17Nd5 can be stable until its peritectic reaction temperature. Based on these experimental results, the Fe−Nd−Pr system was optimized using CALPHAD method, and a set of self-consistent thermodynamic parameters were obtained.