Microstructure and composition analysis of nanostructured materials using HREM and FEG-TEM

The microstructure in nanostructured (NS) materials synthesized by differen t methods have been characterized by electron microscopy methods. NS-Pd was prepared by inert-gas condensation and in situ compacting method (IGCC), N S-alloys by amorphous crystallization method (ACM) and NS-Cu and Cu100-xFex alloy by mechanical alloying (MA) methods. The experimental results have r evealed that different preparation techniques lead to different microstruct ures. The grain boundaries have ordered and disordered structures and high density of defects were frequently detected in NS-materials synthesized by IGCC and MA. For the NS-alloys produced by ACM, however, the structures of GBs are similar to those in coarse-grained materials and the grains have ne arly perfect crystal structure. For immiscible systems, a supersaturated Fe -Cu solid solution can be obtained by MA, but it is difficult using IGCC. ( C) 2000 Elsevier Science Ltd. All rights reserved.