Dislocation substructure in strain cycled copper

A quantitative relationship between cyclic strain range, saturation stress and cell size in polycrystalline copper tubing has been explored by transmission electron microscopy. Controlled cyclic shear strain tests at room temperature and constant cyclic frequency were run on the material at shear strain ranges varying from a minimum of 0.005 in/in to a maximum of 0.020 in/in. It has been found that cell size varies inversely with saturation stress, and small significant changes in cell size accommodate rather large changes in saturation stress . Cell size change has been found to be reversible; small cells become larger when the saturation stress is lowered. The primary means of dislocation interaction is network formation for the strain ranges imposed on this material.Air Force Materials Laboratory 65/04 AF 33 657 10822 65/0