EXAFS STUDIES OF AMORPHOUS FE50TA50 POWDERS DURING MECHANICAL ALLOYING

The progress of the preparation of amorphous Fe50Ta50 alloy powders, s tarting from elemental Fe and Ta crystalline powder mixtures, by mecha nical alloying using a SPEX high energy ball mill was investigated. Th e as-milled Fe50Ta50 powders were examined as a function of milling ti me by scanning electron microscopy (SEM), microhardness, X-ray diffrac tion, differential thermal analysis (DTA), and extended X-ray absorpti on fine structure (EXAFS). The radial distribution functions (RDFs) ob tained from Fourier transformation of EXAFS spectra reveal that there are differences in local atomic structure after prolong milling. When combined with information from other techniques? the results allow the amorphization process for Fe50Ta50 during the mechanical alloying (MA ) to be better understood. (C) 1998 Elsevier Science B.V, All rights r eserved.