Metallographic Preparation of Zn-21Al-2Cu Alloy for Analysis by Electron Backscatter Diffraction (EBSD)
Abstract Samples of Zn-21Al-2Cu alloy (Zinalco) that will be heavily deformed were prepared using five different manual mechanical metallographic methods. Samples were analyzed before tensile testing using the orientation imaging microscopy-electron backscatter diffraction (OIM-EBSD) technique. The effect of type and particle size during the final polishing stages for this material were studied in order to identify a method that produces a flat, damage free surface with a roughness of about 50 nm and clean from oxide layers, thereby producing diffraction patterns with high image quality (IQ) and adequate confidence indexes (CI). Our results show that final polishing with alumina and silica, as was previously suggested by other research groups for alloys that are difficult to prepare or alloys with low melting point, are not suitable for manual metallographic preparation of this alloy. Indexes of IQ and CI can be used to evaluate methods of metallographic preparation of samples studied using the OIM-EBSD technique.
Comparative corrosion behaviour of Zn-2l Al-2Cu alloy and galvanized steel
COMPARATIVE study of the atmospheric corrosion of Zn-2lwt% Al-2wt% Cu(Zn-2IAl-2Cu) alloy, galvanized steel (zinc), and aluminium, was performed exposing them to an urban atmosphere for up to five years. The corrosion rate, determined by weight loss, was greater for the ternary alloy than that for galvanized steel, and very superior to that exhibited by aluminium. Electrochemical tests showed that the longer the exposure time, the greater the protection by the corrosion products. The characterization and morphology of the corrosion products were carried out using scanning-electron microscopy, and X-ray diffraction.
Nuclear spin-lattice relaxation in transition metal compounds with local tetragonal symmetry.
We report on the various contributions to the total spin-lattice relaxation rate in metallic materials with local tetragonal symmetry. The analytical formulae are given in the tight-binding approximation. The calculations show the relation between various partial electron densities of states and corresponding contributions to the relaxation rates. The presented formulae can be used to compare theoretically calculated electron band structure parameters with those obtained from NMR spin-lattice relaxation time measurements.