EXTENDED X-RAY-ABSORPTION FINE-STRUCTURE STUDIES OF HEAT-TREATED FCC-FE50CU50 POWDERS PROCESSED VIA HIGH-ENERGY BALL-MILLING

The local structure and chemistry of a ferromagnetic fcc-Fe 50Cu50 solid solution obtained through high-energy ball milling were measured before and after heat-treatment-induced decomposition using extended x-ray-absorption fine-structure measurements. The decomposition is first evident with the phase separation of α-Fe after a heat treatment at 523 K. Analysis of the residual fcc component revealed that the Fe atoms were predominantly surrounded by other Fe atoms, suggesting that the Fe has coalesced within the fcc structure. The Fe atoms within the fcc phase likely exist in low-spin clusters which provide an explanation for the reduced values of low-temperature magnetization previously measured in annealed samples [P. Crespo et al., Phys. Rev. B 48, 7134 (1993)].