Production and properties of two-phase nanocrystalline Fe/Cu compacts

Bulk granular nanocrystalline materials have been produced from various combinations of a pair of immiscible metals, iron and copper. Nanocrystalline powders were produced by mechanical ball milling and consolidated by warm compaction. Their microstructures were characterized by x-ray diffraction and their strengths determined both in the as-compacted state and after annealing. Both f.c.c. and b.c.c. phases were present in each state of processing. The as-compacted materials were found to have grain sizes in the range 11-13 nm for the iron and 6-9 nm for the copper and were very strong but brittle. Their strength decreased after annealing due to microstructural coarsening. Differential scanning calorimetry performed on the compacts showed some unusual thermodynamic peaks, some of which could be correlated with magnetic transformations.