Effect of nitrogen and methane on the structural and magnetic properties of RFe/sub 2/ (R=Y, Tb and Dy)

Rare earth alloys (R=Y, Tb, and Dy) with MgCu/sub 2/ type crystal structure and the effect of heat treatment in methane and nitrogen gas is studied. The structural and magnetic properties are characterized by Mossbauer spectroscopy. For low heat treatment temperatures (250 to 350 degrees C), C(N) are absorbed resulting in an increased lattice constant. For intermediate heat treatment temperatures, a metastable phase forms in the methane heat treated samples which enhances hard magnetic properties with room temperature coercive fields of 1.4 and 1.1 kOe found in coarse powders of Tb-Fe-C and Dy-Fe-C, respectively. For high heat treatment temperatures (above 450 degrees C), decomposition to RC(RN) and alpha -Fe occurs.<>