29 research outputs found
Molecular structures and vibrations of neutral and anionic CuOx (x = 1-3,6) clusters
We report equilibrium geometric structures of CuO2, CuO3, CuO6, and CuO
clusters obtained by an all-electron linear combination of atomic orbitals
scheme within the density-functional theory with generalized gradient
approximation to describe the exchange-correlation effects. The vibrational
stability of all clusters is examined on the basis of the vibrational
frequencies. A structure with Cs symmetry is found to be the lowest-energy
structure for CuO2, while a -shaped structure with C2v symmetry is the most
stable structure for CuO3. For the larger CuO6 and CuO clusters, several
competitive structures exist with structures containing ozonide units being
higher in energy than those with O2 units. The infrared and Raman spectra are
calculated for the stable optimal geometries. ~Comment: Uses Revtex4, (Better quality figures can be obtained from authors
Effect of processing temperature on the texture and shear mechanical properties of diffusion bonded Ti-6Al-4V multilayer laminates
Two multilayer materials based on Ti-6Al-4V alloy have been processed by diffusion bonding at two different temperatures [1023 K and 1173 K (750 °C and 900 °C)]. The influence of the processing temperature on microstructure, texture, and mechanical properties of the two multilayer materials has been analyzed. Scanning electron microscopy, X-ray diffraction, electron backscatter diffraction, and shear tests have been used as experimental techniques. The multilayer laminate processed at the lowest temperature of 1023 K (750 °C) exhibits mainly transversal texture in the longitudinal plane, which provides an anisotropic mechanical behavior, showing higher shear modulus and maximum shear strength under one of the shear test directions considered. In contrast, diffusion bonding at 1173 K (900 °C) leads to basal/transversal texture because of the partial α → β → α transformation, which provides more isotropic mechanical properties. Accordingly, this laminate shows similar shear modulus and maximum shear strength in different shear test orientationsFinancial support from MICINN (Projects MAT2009-14452 and MAT2012-38962)Peer reviewe