PHASE-TRANSFORMATIONS IN SPUTTERED ND-FE-B ALLOYS

For sputtered NdxFe93-xB7 alloys (x = 9, 11, 13, 15, 16.5) a diagram of the intermediate stages when passing from the amorphous phase to stable crystalline phases is presented. The data were obtained at a heating rate of 20 K min-1 using X-ray diffraction and thermomagnetic and dilatometric methods. In understoichiometric alloys the transition from the amorphous phase to the crystalline phases alpha-Fe and Nd2Fe14B proceeds through formation and decomposition of the metastable phases Nd2Fe16B (type Nd2Fe17, T(c) = 170-degrees-C), Nd2Fe23B3 (T(c) = 380-degrees-C) and epsilon (T(c) = 250-degrees-C). There first appears an alpha-Fe phase in the amorphous solid solution. In overstoichiometric alloys the transition to the structure consisting of Nd2Fe14B and alpha-Nd phases proceeds through intermediate stages with metastable phases Nd2Fe23B3 and chi (T(c) = 170-degrees-C). The first product of crystallization here is the chi phase.