AN EXPERIMENTAL INVESTIGATION OF THE FE-NI-SB TERNARY PHASE-DIAGRAM

The ternary system Fe-Ni-Sb has been investigated in the region betwee n 42 and 100 at.% Sb using conventional methods including DTA, X-ray t echniques, metallography, and electron probe microanalysis (EPMA). A c ontinuous solid solution was found to exist between the NiAs(B8)-type phases Fe1+xSb and Ni1+/-xSb, whereas the marcasite-type phase FexNi1- xSb2 is only stable in the ranges 0.50 less than or equal to x less th an or equal to 1.00 and 0.00 less than or equal to x less than or equa l to 0.03, respectively, A skutterudite-type compound FeNiSb6-isotypic with CoSb3-was found to decompose peritectically at 642 degrees C, An isothermal section of the phase diagram was studied at 600 degrees C by X-ray powder diffraction using the Guinier technique, and the latti ce parameters of FexNi1-xSb2 and (FeyNi1-y)(1+/-x)Sb were determined a s a function of composition, Several samples were investigated by micr oprobe analysis to fix the phase boundaries of the (FeyNi1-y)(1+/-x)Sb -phase. Four invariant ternary reactions were found in the Sb-rich par t of the phase diagram, all of them within the narrow temperature rang e between 615 and 642 degrees C, The results of the DTA measurements w ere also used to construct the liquidus surface in the entire composit ion range investigated, All experimental information was combined with literature data to yield a complete ternary phase diagram in the comp osition range between 42 and 100 at.% Sb.