EFFECTS OF SHOCK LOADING ON THE LATTICE OF A SILICON BRONZE WITH LOW STACKING FAULT ENERGY.
MARTIN CO ORLANDO FLA MATERIALS RESEARCH LAB
Pagination or Media Count:
Effects of shock loading on the lattice of silicon bronze with low stacking fault energy were studied by postmortem analysis. Crystal imperfections introduced by shock loading up to 420 kbar were studied primarily by X-ray diffraction. Specimens were 30 mm long and 2 x 2 mm in cross-section the shock pressure was applied to one of the 2 x 30 mm faces. By spinning the specimens at 200 rpm about the long axis, a DebyeScherrer geometry could be employed for the X-ray work. The macroscopic plastic strains determined from dimensional changes of the specimens varied linearly with shock pressure, whereas the slope of hardness versus pressure was initially steep and then asymptotically approached a limiting value. Analysis of the position and width of X-ray diffraction line profiles showed 1 some formation of deformation stacking faults 2 a decrease in domain size to a lower limiting value reached at fairly low about 100 kbar shock pressures 3 essentially no rms strain in any of the specimens even after loading to maximum shock pressure. Observations are consistent with the formation, by shock loading, of micro-twins and faults as the principal lattice imperfections. In addition, evidence was found for a polymorphic transformation between 130 and 200 kbar. Author
- Metallurgy and Metallography