XANES analysis of bcc/fcc two-phase binary alloys

A critical factor in the characterization of two-phase binary alloy systems is the determination of the phase fractions and compositions of the two coexisting solid solutions for any given overall composition of the two-phase mixture. In some systems, for example nanocrystalline alloys formed by high-energy ball-milling, these parameters are difficult to attain by traditional techniques like X-ray diffraction. A new technique has been developed to obtain these quantities indirectly from X-ray absorption near edge structure (XANES) data collected at the two relevant absorption edges, with the formulation of this technique presented here in detail. The technique has been tested using Fe-Ni fcc and bcc standards and the results indicate that the method is accurate to within 5%. This method has been applied to two-phase (f.c.c. and b.c.c.) binary alloys formed by ball-milling of Cu_100-xFe_x (x = 50-80).