Structural study of TM60Ti40 (TM = Fe, Co, Ni) amorphous alloys produced by mechanical alloying

This paper describes the determination of the local atomic structure of amorphous TM60Ti40 (TM = Fe, Co, Ni) alloys produced by mechanical alloying (MA) technique. The interatomic distances and the coordination numbers for the TM-TM, TM-Ti and Ti-Ti first neighbors were obtained by making the deconvolution of the first atomic shells of the radial distribution functions, which were calculated from the measured X-ray scattering patterns for the three alloys. The deconvolution was possible because the local atomic structures of these alloys can be accurately predicted by the additive hard-sphere (AHS) model. Thus, the number of TM TM and TM-Ti first neighbors given by the AHS were used in the deconvolution to find the number of minority Ti-Ti pairs. Our results show complete amorphization for the Ni60Ti40 and Co60Ti40 alloys and partial amorphization in the case of the Fe60Ti40 alloy, These results are consistent with the free enthalpies of mixing for these alloys. A chemical short-range order, greater than expected, was found in the Fe60Ti40 alloy and attributed to partial amorphization of the Fe-Ti system by MA. (C) 2002 Elsevier Science B.V. All rights reserved.