PREPARATION AND THERMAL-STABILITY OF NANOCRYSTALLINE CU ALLOYS

Immiscible Cu alloys (Cu-Ag, Cu-Ta, Cu-W) have been prepared by using the following two methods: (a) inert gas condensation followed by an i ntegrated cold compaction step and (b) high-energy ball milling. Duple x microstructures obtained from evaporation of a prealloy or by ball m illing of the respective elemental powder ingredients are thermally ra ther stable and show homogeneous grain growth. The specific heat of me chanically alloyed Cu-W shows an anomalous behaviour for milling times around 25 h indicating a minimum in the thermal stability at an inter mediate stage of mechanical deformation.