Abstract
Annealed tough pitch copper containing Cu2O inclusion particles has been pressurized under various pressures up to 15000 kg/cm2 at room temperature and the dislocation structure formed by pressurizing has been studied by means of transmission electron microscopy. The results obtained are as follows: (1) The critical pressure required to generate dislocations and to form tangled dislocations around a Cu2O particle depends strongly on the particle diameter. The relation between the critical pressure and the particle diameter agrees well with the theory of Ashby et al. (2) The tangled dislocations show regular structures whose shape changes with the orientation of the foil specimen. This phenomenon is successfully explained by a mechanism of the tangle formation through the interaction between the dislocations generated on the surface of an inclusion particle. (3) The maximum range D of the dislocation tangle is proportional to the diameter of the inclusion particle d and increases with increasing pressure. The value of the ratio D⁄d is about 3 at 5000 kg/cm2 and about 7 at 15000 kg/cm2. (4) The dislocation tangles formed around the inclusion particles act as obstacles to the motion of dislocations when a pressurized specimen is deformed and causes the change of its mechanical properties.
