Oxidation of copper alloys studied by analytical transmission electron microscopy cross-sectional specimens

In this work, the oxide structures of three polycrystalline copper grades, unalloyed oxygen-free (OF) copper and alloyed CuAg and deoxidized high-phosphor (DHP) copper, were studied using cross-sectional analytical transmission electron microscopy (AEM) samples. The oxidation treatments were carried out in air at 200 and 350 °C for different exposure times. The detailed oxide layer structures were characterized by AEM. At 200 °C, a nano-sized Cu2O layer formed on the all copper grades. At 350 °C, a nano-sized Cu2O layer formed first on the all copper grades. After longer exposure time at 350 °C, a crystalline CuO layer grew on the Cu2O layer of the unalloyed OF-copper. In the case of the alloyed CuAg- and DHP-copper, a crystalline and columnar shaped layer, consisting of Cu2O and CuO grains, formed on the nanocrystalline Cu2O layer. At 350 °C, the unalloyed copper oxidized notably slower than the alloyed coppers, and its oxide structures were different than those of the alloyed coppers.

Specimen Preparation of Thin Crystalline Fibers for Transmission Electron Microscopy

ABSTRACTA technique was developed to prepare crystalline fibers of less than 1 mm diameter for transmission electron microscopy. Cross sections were made by casting a short piece of the fiber in an epoxy resin, sectioning the block, and laminating the slices against thin glass discs for stability before dimpling. Longitudinal sections were reinforced in a similar manner. TEM tungsten rings were sometimes used as an alternative method to add stability to the longitudinal sections. The technique was especially developed for Bi-Sr-Ca-Cu-O compounds but is also suitable for other materials.