Comparisons of Nanocrystalline Cu, Ag, and Al Prepared by Room-Temperature-Molding Method and Vacuum-Warm-Compaction Method

Nanocrystalline nonferrous metals (Cu, Ag, and Al) were fabricated by room-temperature-molding method and vacuum-warm-compaction method, respectively. X-ray diffraction, Positron annihilation spectroscopy, and density test were utilized to characterize these as-prepared nanocrystalline specimens. The thermal stability and micro-void distribution of the as-prepared nanocrystalline metals were compared and discussed in detail. The experimental results show that the increasing of density is unremarkable while the microstrain reduces during warm-compaction process. The nanocrystalline nonferrous metals prepared by VWC have better thermal stability. Positron annihilation spectroscopy analysis indicates that, compared with the specimens prepared by RM, the average size of micro-void and proportion of single vacancy is a little larger in nanocrystalline copper fabricated by VWC.