Alloys with the composition RE2Fe17and RE2Fe15X2(X=Al,Ga) have been synthesized by the archyphen;melting technique followed by an 125hyphen;h anneal at 900ndash;1000thinsp;deg;C in evacuated silica capsules. The new compound Nd2Fe15Ga2is unstable below 800thinsp;deg;C, and is only obtained by quenching from above 900thinsp;deg;C. From xhyphen;ray powder diffraction analysis all alloys except Pr2Fe15Ga2were found to crystallize with the hexagonal Th2Zn17type; indications for a preferential occupation of the (6c) sites by the X atoms are small. Substitution of Al, Ga atoms generally leads to a large increase of the Curie temperature and of the magnetocrystalline anisotropy, thereby enhancing the remanence as well as the coercivity. These effects are a consequence of the strongly distancehyphen;dependent exchange interactions of the Fehyphen;Fe and Fehyphen;RE coupling mechanisms. As for binary Pr2Fe17, the easy axis of magnetization for Pr2Fe15Al2was found to be in the basal plane.
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