Investigation of the δ and μ phases in the Nd-Fe-Al system

Nd-Fe-Al alloys containing either a delta or mu phase (Al content in the 2.5-11 at.% range) were studied by x-ray diffraction analysis and Mossbauer spectrometry. A lattice expansion of the delta phase (composition Nd sub 6 Fe sub 14-x Al sub x ) is observed, due to the substitution of Al for Fe in the 16l sub 2 site of space group I4/mcm. The room-temperature Mossbauer spectrum is paramagnetic for x=2.8 and magnetic for x=2. For x=2, the mean iron moment is estimated to be 2.0plus/minus0.1 mu sub B . Room-temperature Mossbauer spectra of the mu phase (Nd sub 33.3 Fe sub 66.7-x Al sub x with x=5.3 and 3.7) are magnetic, and the results support a slight distribution of environments around the Fe atoms due to the substitution of Al for Fe.