MAGNETIC FE17R5 IN THE FE-ND AND FE(-TI)-SM SYSTEMS, AND OTHER PHASES IN FE-ND

With the help of a calculated full powder diffraction pattern of hexagonal Fe17Nd5, a = 2.0214 nm, c = 1.2329 nm, it is verified that the phase has been observed under different experimental conditions: in binary Fe-Nd by annealing at 600-degrees-C, in melt-spun Fe-Nd by annealing at 577-degrees-C, and in Fe-Nd-O by reaction sintering followed by a 600-degrees-C anneal. The same X-ray diffraction fingerprint is found in Fe(-Ti)-Sm where it had been synthesized by cathodic sputtering, or by mechanical alloying. Whereas the Sm phase is magnetically hard, the Nd phase is not. Other phases observed in the Fe-Nd system, in addition to Fe17Nd2 and Fe17Nd5, are metastable Fe7Nd, which can be stabilized by adding Ti, and a magnetically hard phase, also with 12.5 at.% Nd, T(c) = 230-degrees-C, which is possibly impurity stabilized. The three forms of the Nd solid solution, in polytype notation, hexagonal 4H and 2H, and cubic 3R can be observed under the following conditions: 4H in as-cast alloys, 2H in rapidly solidified binary Fe-Nd, and 2H and 3R in sintered Fe-Nd-B magnets. 3R and 2H are stabilized by impurities (oxygen) and can also contain dissolved Fe which is likely to be interstitial.