MILLING AND MECHANICAL ALLOYING OF COPPER AND SOME SOLUTION ALLOYS SEEN AS A THERMOMECHANICAL PROCESS

During the milling of elemental copper or mixtures based on copper an intense cold worked structure is built up which leads to orientation dependent internal strains and an isotropic internal stress. The extent of this retained stress varies with alloying as the stacking fault energy changes and the rate of stress relaxation is altered. The material produced at this stage is of moderate grain size containing an intense dislocation cell structure. Examinations of other elemental metals show that the amount of internal stress and the final grain size vary according to the ease of dislocation relaxation and recrystallization processes. Annealing treatments given after milling lead to stress relaxation and simultaneously grain refinement by recrystallization may occur. According to these results milling and subsequent annealing can be regarded as a thermomechanical process allowing significant microstructural modifications.