부산대학교 도서관

A new compaction unit was installed for consolidation at high temps. SANS of nanocrystalline (n-) Pd and Cu confirms presence of pores close to the grain size; high scattering angles indicated large amounts of hydrogen (H). Confirmation was obtained from prompt gamma activation analysis. Compaction at high temps, preheating the powders before compacting, or a post-consolidation anneal, greatly lowers the H content. SANS showed that annealing expands voids in samples with high H content, but voids shrink if the H has been removed. Elastic modulus in n-Fe was measured using a nanoindenter; results indicate that the diminution of modulus in n-metals can be explained entirely on the basis of porosity. Detailed x-ray measurements were made on n-Pd to examine the frequency of twins and stacking faults; results will be compared to TEM. A new chamber is being constructed for the inert gas condensation equipment, for improved vacuum.