[en] A difference of amorphous structures of magnetic Nd_4.5Fe₇₇B_18.5 alloys formed under two different cooling rates was investigated by means of electron microscopy, electron diffraction and X-ray diffraction techniques. In spite of no appreciable difference in the high resolution electron microscope images, an atomic structural difference especially in the B-centered polyhedral structures was found in these specimens in their as-formed states. The effect of the initial local structure difference on the process of primary crystallization in these alloys on annealing was discussed. (author)