ALLOY EFFECTS IN CONSOLIDATED BINARY-MIXTURES OF NANOMETER-SIZED CRYSTALS INVESTIGATED BY MOSSBAUER-SPECTROSCOPY

In this paper, investigations by Mössbauer spectroscopy of binary mixtures of Fe crystals and Cu or Ag crystals are reported; the crystal sizes of the constituents are in the range of 6-20 nm. In the case of the Fe/Cu system, samples containing small iron concentrations (about 1 at %) as well as samples with about 30 at % Fe were examined; in the case of Ag/Fe, results for 30 at % Fe are reported. The principal finding is that the Mössbauer spectra show components different from α-Fe which may be identified, by comparison with metastable Cu/Fe or Ag/Fe alloys generated by co-sputtering, as alloy phases of the constituent elements although Cu/Fe as well as Ag/Fe alloys exhibit little or no solubility. The formation of alloy phases is proposed to occur at the grain or interphase boundaries between the crystals and seems to be based on the enhanced free volume and/or local strain fields at the interfaces. © 1990.