Atomic structure and magnetic properties of Cu80Co20 nanocrystalline compound produced by mechanical alloying

Direct observation of the atomic structure of the mechanically alloyed Cu80 Co20 compounds has been made using the field ion microscope (FIM). Phase co mposition, defect structure and morphology of material on the atomic scale have been determined. It has been established that the studied material is chemically inhomogeneous, presenting a mixture of two main phases: heteroge neous solid solution of cobalt in copper, and pure cobalt. Phase volume rat ios, particle and cluster sizes have been estimated. An evaluation of Co co ntent in Cu-Co solid solution has been made. The width of interfaces in thi s mechanically alloyed material was revealed to be at least twice the width of phase boundaries in metals and alloys. Superparamagnetism of the compou nd studied at elevated temperatures and saturation magnetization deficit at low temperatures are discussed on the basis of the above-mentioned structu ral data. (C) 1999 Elsevier Science B.V. All rights reserved.