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A Cu-1Cr-0.1Zr alloy has been subjected to ECAP processing via route Bc and aging at 250-800°C. Electron BackScatter diffraction (EBSD), Transmission Electron Microscopy (TEM) and X-Ray Diffraction Line Profile Analysis (XRDLPA) techniques have been used to unveil some peculiarities of the grain and subgrain structure with a special emphasis on the comparison of the grain size estimated by the three techniques. For the alloy ECAP processed and aged up to 16 passes, the grain size (from EBSD, 0.2 < d < 5 µm), subgrain size (from TEM, d ~ 0.75 µm) and "apparent" average crystallite size (from XRDLPA, d < 0.25 µm) are manifestly different. The results were compared to the published data and analyzed based on the fundamental aspects of these techniques. [ABSTRACT FROM AUTHOR]

First stages of recrystallization are analyzed in low stacking fault energy nickel alloys cold rolled and subsequently annealed at 700 °C for 6 min. These alloys are envisaged as candidate materials for the heat exchanger of very high-temperature reactor that works at 1000 °C. First recrystallized grains show evidence of extensive twinning that is studied by transmission electron microscopy. Specific twinning features such as fivefold twin and microtwins bordered by partial dislocations are revealed. Twin density increases with increasing amounts of prior deformation before annealing. The local crystal orientations are determined at a nanometer scale. It is shown directly that when twinning occurs, the recrystallized area beyond the twin has a lower stored deformation energy. Thus, recrystallization and the associate twinning induce a decrease in the total stored deformation energy. [ABSTRACT FROM AUTHOR]

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Excellent mechanical properties of oxide-dispersion-strengthened (ODS) alloys arise from a high density of Y-Ti nano-oxides finely dispersed in the matrix. Characteristics of this precipitation can strongly be influenced by oxygen contamination during milling. We studied an as-received and annealed (1 h 1150 °C) oxygen-enriched ferritic ODS alloy by High Resolution Transmission Electron Microscopy. The as-received sample has unknown b.c.c nano-oxides, while the annealed one has orthorhombic nanoparticles. We propose a phase relaxation during the annealing, confirmed by the observation of a particle where both cubic and orthorhombic structures coexist. The influence of oxygen on the particle structure is also discussed. [ABSTRACT FROM AUTHOR]

Abstract: The joining of a 1.2mm thickness Al 6016 to a 2mm thickness IF-steel has been performed by friction stir spot welding (FSSW). The intermetallic compounds (IMC) have been identified at the interface Al 6016/IF-steel and quantified as a function of the rotational speed and tool penetration. TEM observations indicated the presence of tangles of elliptical intermetallic compounds. FeAl3, Fe2Al5 and FeAl2 were identified depending on welding conditions. The influence of IMC on tensile shear strength has been established. An IMC layer seems necessary to improve the weld strength, but if the layer is too thick, cracks initiate and propagate easily through the hard IMC tangles. [Copyright &y& Elsevier]