Ti-25Ni-25Cu and Ti-25M-23Cu-2Mn (at.%) ribbons were melt spun at 26 m s(-1). Transmission electron microscopy (TEM) investigations proved that the Mn addition lowers the amount and reduces the size of the beta phase crystallites present in the otherwise amorphous matrix. The observations using the (10 0) superlattice spot proved that each crystallite forms a single antiphase domain. The planar AL-CHEMI experiments at (000, 100) orientation of thin foils from as-spun ribbons confirmed a high occupancy of the Ni-rich planes by Cu and Mn additions. However, even as practically all Mn atoms found their places on the Ni-rich planes, though a small amount of Cu atoms still occupy the planes characteristic for Ti atoms. The transfer of the remaining Cu atoms from Ti {100} to Ni {100} planes might be the reason of the rise of the temperature of the start of the martensite transformation (M-s) during further heat treatment. (C) 2003 Elsevier Science B.V. All rights reserved.