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Three kinds of thin AZ31 wrought magnesium alloys sheets were used in order to investigate the influence of the second phase particles on fracture toughness. From the theoretical model, the ratio of λp/dp would be estimated 5~ 6. On the other hand, from the microstructural observation, average particle spacing on each material was sample A: 13.1µm, sample B: 14.1, and sample C: 12 µ. In addition, average particle size on each sample was sample A: 2.1, sample B: 1.9, and sample C: 2.3 µm. Therefore, the ratio of λp/dp calculated from fracture surface observation would be predicted 6 ~ 7. In comparison with the result of the prediction by theoretical analysis was in good agreement with the result of fracture toughness observation. It was found that the variation in plane-strain fracture toughness on AZ31 were affected by both of particle spacing and particle size.

Plastic formability in the secondary processing of an AZ31 magnesium alloy was investigated using fine-grained and relatively coarse-grained materials, respectively. To produce components for mobile electric appliances, boss formability was examined at a relatively low temperature of 523 K. The boss with a height of 14 mm was successfully formed in fine-grained material under a nominal forming pressure of 582 MPa in 5 s. Analysis of the boss forming revealed that the forming occurred under the high-strain-rate superplastic condition. The grain size in the boss region was slightly coarsened, probably as a result of strain-induced grain growth, which is a widespread property of superplastic flow. On the other hand, even in the coarse-grained material, a relatively high boss height of 5 mm was obtained under the same forming condition. After the boss forming, grain refinement was observed in the coarse-grained material. It was suggested that the coarse-grained materials exhibited relatively high formability because of dynamic recrystallization. It was concluded that plastic forming concomitant with grain growth was more effective than that concomitant with grain refinement in AZ31 magnesium alloy. An empirical equation to perform plastic forming under the condition concomitant with grain growth was developed.

There are few reports about plane-strain fracture toughness on wrought magnesium alloys. Also, there are a little data, for example plane-strain fracture toughness, that evaluates such as reliability and safety in magnesium alloys. Therefore, in this study, plane-strain fracture toughness, K IC , on thin AZ31 wrought magnesium alloy sheets was analyzed. As a result, appropriate plane-strain fracture toughness was not obtained by plane-strain fracture toughness test. It was because specimens used in this study were too thin to satisfy small scale yielding condition. But, as a result of stretched zone analysis, appropriate plane-strain fracture toughness, K IC , was obtained and the values of K IC were 16.5-18.4 MPam 1/2 . According to the result of this study, it is concluded that stretched zone analysis Was one of effective ways to evaluate fracture toughness of AZ31 wrought magnesium alloy appropriately. And the values of fracture toughness on AZ31 wrought magnesium alloys were equal or higher than that of cast magnesium alloy.

The past benefit evaluation of the flood control works is nothing but object of reducing damage cost, don't seize change for state probability, that is uncertainty, land use change due to location choice action, and extend effect.In this paper, we constructed Location Equilibrium Model based on multispace general equilibrium theory under uncertainty. And we defined the benefit, expanded the concept of Equivalent Variation, proposed Non-Contingent EV including the benefits of change for state and location choice probability, as the most rational definition for evaluation.The applicable possibility of Location Equilibrium Model, Benefit Evaluation was shown through a case study.

We have studied the structural change of targets and the ablated particles to classify the characteristics of laser ablation. Neutral atoms, positive ions and global particles are generated from metal targets irradiated by the KrF excimer laser beam. The average energy of 100∼180 eV per atom is required to ablate atomic particles. The targets after irradiation show the change of surface morphologies and X‐ray diffraction patterns due to heating. The change of chemical compositions and the resolidified layer are not observed.

The KrF laser ablation of Al, Cu, Si, and SrTiO3 targets has been studied using an electrostatic deflection energy analyzer and a quadrupole mass filter. Beam like ions appear to accompany ablation. The average kinetic energies of Si+ and metal ions are about 45 eV and 60 eV, respectively. The energies of ions are ranked in the order of Si3. The mean ion energy of Cu+ is not affected by the laser fluence range of 2-7.5 J/cm2.

Proposition d'une equation entre la deformation plastique de transformation et la contrainte appliquee. Application du modele, des aciers non allies ou faiblement allies. Comparaison avec des resultats experimentaux

The Ullmann coupling of 1-bromo-2-naphthoates of C-chiral alcohols of R- and S-configuration induced axial dissymmetry of R- and S-chirality, respectively, in the newly formed 1,1′-bond of the binaphthyls; the optical yield amounted up to 13% where the chiral alcohol was l-menthol.

The applicability of high-strain-rate superplasticity for forming magnesium parts, especially structural component with a boss on a plate designed with the aim of producing mobile electric appliances, was examined. The required microstructure and grain refinement process for target forming was examined prior to the forming trials. Following the examination of the processing design, the high-strain-rate superplastic AZ91 magnesium alloy with a required grain size less than 3.2 μm was produced by hot extrusion under the condition that the Zener-Hollomon parameter was 3 x 10 1 2 s - 1 . It was experimentally confirmed that a boss with a height greater than 5 mm, which is a requirement for electric appliances, could be formed within 10s even at a low temperature of 523K using this high-strain-rate superoplastic magnesium alloy. Basic knowledge related to the formation of three-dimensionally shaped magnesium parts by utilizing high-strain-rate superplasticity was obtained.