Characterization of nanoscaled heterogeneities in mechanically alloyed andcompacted CuFe

Cu80Fe20 and Cu50Fe50 were mechanically alloyed from the pure elements by b all milling for 36 h. The alloy powder was compacted into tablets at room t emperature by applying a pressure of 5 GPa. Characterization of the Cu80Fe2 0 and Cu50Fe50 alloys was carried out by high-resolution transmission elect ron microscopy (HREM), atom probe field ion microscopy and three-dimensiona l atom probe (3DAP). The grain size of the nanocrystalline microstructure o f the ball-milled alloys observed with HREM varies between 3 and 50 nm. Ato m probe and 3DAP measurements indicate that the as-prepared state is a high ly supersaturated alloy, in which the individual nanocrystals have largely varying composition. Fe concentration in Cu was found to range from about 8 to 50 at%. It is concluded that by ball milling and compacting an alloy is produced which on a nanometer scale is heterogeneous with respect to morph ology and composition. (C) 2001 Elsevier Science B.V. All rights reserved.