Microstructural characterisation of Fe-Cr-P-C powder mixture prepared by ball milling

摘要

In an attempt to prepare amorphous Fe_(77)Cr_4P_8C_(11) alloy by mechanical alloying, powder mixtures of Fe, Cr, P and C (activated carbon) with a purity of 99.9 percent have been ball milled, under argon atmosphere for several periods up to 90 h, in a planetary ball mill (Fritsch P7). The structure and microstracture of the milled powders have been characterised, as a function of milling time, by X-ray diffraction and Mossbauer spectrometry. During the first stage of milling (up to 12h), detailed analyses of the diffraction patterns and the Mossbauer spectra reveal a complete dissolution of the elemental powders and the formation of Fe_xP (1 < x < 2), Fe_3P phosphides and Fe_3C carbide in addition to alpha-(Fe,Cr) phase. The amoiphous like state is reached after 32 h of milling. Further milling leads to the appearance of new carbides such as (Fe,Cr)_7C_3 and epsilon'-Fe_(2.2)C with the phosphide (Fe,Cr)_3P type phase embedded in the amorphous matrix.