A STUDY OF CU50FE50 PRODUCED BY MECHANICAL ALLOYING AND ITS THERMAL-TREATMENT

A specimen of Cu50Fe50 equiatomic composition was mechanically alloyed (MA) by ball milling starting from the pure elements, which are immis cible according to the equilibrium phase diagram. Structural analysis by x-ray and neutron diffraction has shown that the mechanical process initially reduces the crystallite size of both elements as a function of the milling time. The diffraction data show that the bcc iron phas e is subsequently consumed, due to progressive incorporation of the ir on atoms into the fcc copper matrix. The Mossbauer spectra of a specim en MA for 16 h has a broad magnetic profile typical of a Fe-Cu extende d solid solution, with some evidence of two local environments of the iron atoms and a small admixture of the gamma-Fe. The annealing of the se MA treated specimens effects a decomposition of the extended solid solution into FCC copper and both alpha- and gamma-iron allotropes. Th is decomposition process is discussed in relation to spinodal decompos ition and to nucleation-and-growth mechanisms.