CHROMIUM EFFECT ON SOME PROPERTIES OF MELT-SPUN AMORPHOUS AND NANOSTRUCTURED ALLOYS

The influence of chromium content on the structure, thermal properties and Curie temperature of (FexCr1-x)(735)Cu1Nb3Si135B9 (x=0.85-1.0) al loys in the form of rapidly quenched ribbons is described. The structu re of the samples in the amorphous and nanocrystalline state has been studied by transmission electron microscopy (TEM). Chromium alloying r esults in the refinement of the nanocrystalline grains. From different ial thermal analysis (DTA) it is evident that the Cr addition leads to the shift of the first DTA crystallization peak (crystallization of a lpha-FeSi phase embedded in amorphous matrix) to the higher temperatur es and to the narrowing of the interval between the first and the seco nd exothermic peak (formation of Fe, Nb borides). Perhaps the formatio n of Cr borides (thermodynamically more stable than FeNbB) within the temperature range 1180-1260 K is observed on DTA curves. In the case o f alloy without Cr the third exothermic peak was nor present. Curie te mperature decreases with increasing Cr content. (C) 1998 Acta Metallur gica Inc.