The ultra-fine grained (UFG) aluminum with the grain size of 260 nm was fabricated by annealing for the severely plastic deformed A1100 alloy. This UFG aluminum showed the 0.2% proof stress (σ 0.2) of four times the stress that the conventional Hall-Petch relation showed. In this study, for the UFG aluminum, the fine-grained (FG) aluminum with the grain size of 960 nm and the coarse-grained (CG) aluminum with the grain size of 4.47 µm, dislocation density change during the tensile deformation was investigated by the In-situ XRD measurement using SPring-8. The dislocation density changed in four stages with increase in strain. The first stage was the elastic deformation region and the dislocation density hardly changed. Only in the CG aluminum, this stage was hardly observed and the stress in which the dislocation began to multiple (σ I) was almost 0 MPa. In the second stage, the dislocation density rapidly increased to ρ II in which plastic deformation became possible at constant strain rate. In the third stage, the change became moderately. In the fourth stage, the dislocation density rapidly decreased by the fracture of test pieces. Additionally, the σ 0.2-σ I were followed the conventional Hall-Petch relation regardless of grain size.

The detail structure of heavy rust layers with large swelling and laminated layers formed on weathering steel bridges have been investigated by optical microscope and laboratory powder X Ray diffraction (XRD) and synchrotron XRD in SPring 8. Some large gaps (inter layer) and many linearly arrayed voids (LAV) were found along layers. The mass ratio of spinel type iron oxide [mainly Magnetite (Fe 3 O 4 )] in average composition of the whole layer was 30 40 mass. In contrast the mass ratio of spinel in its local parts, i.e. outer layer, inter layer and inner layer position was not higher in common but mass ratio of b FeOOH was higher. Thus we propose a multilayer model structure for these unique rust layers which are made of Spinel Poor, Rich and Poor unit cell structure (SPRaP cell) compartmentalized by LAV.

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Synopsis:The Nb 3 Sn strands used for the fusion reactor of the ITER are made up of a typical composite material consisting of a brittle superconducting intermetallic compound. Thermally induced strain is inevitably generated in the composite due to different coefficients of thermal expansion and different moduli of elasticity among the constituent components. In order to evaluate the thermal strain exerted on superconductive filaments quantitatively, local strain measurements were carried out during heating and cooling using quantum beams. The stress versus strain curves of the Nb 3 Sn strand showed a typical elasto-plastic behavior, which could be numerically evaluated on the basis of the rule of mixture. The local strain exerted on superconductive filaments along the axial direction was compressive at room temperature and tensile at high temperatures. Recently, a numerical method to evaluate temperature dependence was proposed. The present paper reconfirms that the temperature dependence of the thermal strain can be reproduced well using the proposed numerical calculation.