XRD AND EXAFS INVESTIGATION OF THE DECOMPOSITION OF CO-CU SOLID-SOLUTION PREPARED BY MELT-SPINNING

High solid-solubility Co15Cu85 alloys were prepared by melt spining an d then submitted to isothermal and anisothermal annealing to obtain gr anular alloys. The synchrotron radiation X-ray diffraction patterns an d extended X-ray absorption fine structure (EXAFS) spectra were measur ed to investigate the decomposition of supersaturated solid solution u pon annealing. Experimental results indicated the precipitation of ult rafine Go-rich particles occurred at about 500 degrees C and the annea ling had a great influence on the middle-range order of Co atoms. Whil e the fitted EXAFS spectra showed that the interfaces of Co precipitat es seem to be enriched with vacancy-type defects, leading to distorted interfaces.