The Microstrain Region in High-Purity Refractory Metals

摘要

The behavior of dislocations in single crystals of high purity molybdenum has been inferred from dynamics tests conducted in the micro and macrostrain regions and studied more directly by making dislocation velocity measurements. All the observations can be shown to be self consistent on the basis that dislocation mobility is controlled by the overcoming of Peierls-Nabarro hills by the nucleation of double kinks. The presence of internal elastic stresses is responsible for reversible anelastic stress-strain behavior in the microstrain region extending up to strains of the order 0.001. The magnitude of the effective stress tau throughout the stress-strain curve was measured and its effect on the controlling deformation process is analyzed. Related investigations of the production and structure of extra-high purity molybdenum, the reliable etch pitting of dislocations and the defect structure of deformed and quenched molybdenum are also described.