The recovery of cold-worked molybdenum

Molybdenum wires of 0.05 mm diameter were drawn at room temperature from an electron beam refined rod. These wires were subsequently subjected to isochronal and isothermal annealing treatments in a temperature range from 300 to 1200 K. The electrical resistivity is shown to decrease in four stages: stage III (300-500 K), stage IV (500-700 K), stage V (700-900 K) and stage VI (900-1200 K). These stages are associated with activation energies of 1.3 eV, 2.5 eV and 3.7 eV, respectively. The kinetics of the pronounced stage III recovery are compatible with a diffusion controlled bimolecular reaction. It is proposed that stage III is mainly due to free migration of interstitials to vacancies, stage IV to free migration of remaining vacancies, stage V to dislocation rearrangements and annealing and stage VI to recrystallization.